Absorbent article with increased wet breathability

ABSTRACT

An absorbent article includes a vapor permeable backsheet, a liquid permeable topsheet positioned in facing relation with the backsheet; and an absorbent body located between the backsheet and the topsheet. The absorbent body may include multiple zones of high air permeability or may include materials which provide improved air exchange after being wetted. The absorbent article may also include a ventilation layer between the absorbent body and the backsheet and a surge management layer between the absorbent body and the topsheet. The article exhibits improved air exchange within the article during use. As a result, the article exhibits substantially reduced levels of hydration of the wearer&#39;s skin when in use which renders the skin less susceptible to the viability of microorganisms.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to an absorbent article forabsorbing body fluids and exudates, such as urine. More particularly,the present invention relates to absorbent garments, such as disposablediapers and adult incontinence garments, which are configured to absorbbody exudates while also helping to provide reduced skin hydration andimproved skin health.

[0003] 2. Description of the Related Art

[0004] Many known diaper configurations employ absorbent materialslocated between a liquid pervious topsheet and a vapor and liquidimpermeable backsheet. Such backsheets are well suited to prevent themigration of liquid waste from the absorbent materials to the outergarments of a wearer. Unfortunately, the use of liquid and vaporimpermeable backsheets can result in a high degree of humidity withinthe diaper when in use which may increase the temperature of thewearer's skin and result in relatively high skin hydration levels. Theocclusive, moist environment inside diapers incorporating suchbacksheets can promote the viability of microorganisms, includingCandida albicans, which can undesirably lead to the onset of diaperdermatitis (diaper rash).

[0005] Diaper dermatitis can afflict almost every infant at some timeduring the diaper wearing years. The most severe form of this conditionis usually caused by secondary infection with the fungi Candidaalbicans. Although other factors influence the pathogenesis of thisfungi, one critical factor is the relative humidity within the diaperwhich is directly related to the occlusion or semi-occlusion of thediaper area.

[0006] In order to reduce the humidity level within diapers, breathablepolymer films have been employed as outer covers for absorbent garments,such as disposable diapers. The breathable films are typicallyconstructed with micropores to provide desired levels of liquidimpermeability and air permeability. Other disposable diaper designshave been arranged to provide breathable regions in the form ofbreathable panels or perforated regions in otherwise vapor-impermeablebacksheets to help ventilate the garment.

[0007] Conventional absorbent articles, such as those described above,have not been completely satisfactory. For example, articles whichemploy perforated films or breathable panels can exhibit excessiveleakage of liquids from the article and can excessively soil thewearer's outer garments in the regions of the perforations or panels. Inaddition, when the absorbent material of the article becomes loaded withliquid, the wet absorbent can block the escape of moisture from thewearer's skin. Such absorbent garment designs have not been able tomaintain a high level of breathability when wet to sufficiently reducethe hydration of the wearer's skin. As a result, the wearer's skin hasremained susceptible to rashes, abrasion and irritation.

SUMMARY OF THE INVENTION

[0008] In response to the difficulties and problems discussed above, anew disposable absorbent article which has an increased air exchangerate when wet and, as a result, reduced levels of skin hydration hasbeen discovered.

[0009] As used herein, reference to “air exchange” refers to thetransfer of air and, in particular, humid air from the interior of anabsorbent article, when in use on a wearer, to the exterior of theabsorbent article (ambient atmosphere) which allows drier ambient air tomove into the absorbent article.

[0010] As used herein, a substantially liquid impermeable material isconstructed to provide a hydrohead of at least about 60 cm(centimeters), desirably at least about 80 cm, and more desirably atleast about 100 cm. A suitable technique for determining the hydroheadvalue is the Hydrostatic Pressure Test which is described in furtherdetail herein below.

[0011] As used herein, a substantially vapor permeable material isconstructed to provide a water vapor transmission rate (WVTR) of atleast about 100 g/sq.m/24 hr, desirably at least about 250 g/sq.m/24 hr,and more desirably at least about 500 g/sq.m/24 hr. A suitable techniquefor determining the WVTR value is the Water Vapor Transmission Rate Testwhich is described in further detail herein below.

[0012] In one aspect, the present invention relates to an absorbentarticle which comprises an absorbent, a front waist section, a rearwaist section and an intermediate section which interconnects the frontand rear waist sections. The absorbent article defines a Wet AirExchange Rate of at least about 190 cubic centimeters per minutecalculated according to the Tracer Gas Test set forth herein. In aparticular embodiment, the article defines a Wet Air Exchange Rate of atleast about 200, desirably at least about 225 and more desirably atleast about 250 cubic centimeters per minute calculated according to theTracer Gas Test. The absorbent article may further define a Dry AirExchange Rate of at least about 525 cubic centimeters per minutecalculated according to the Tracer Gas Test and/or a Skin HydrationValue of less than about 18 grams per square meter per hour calculatedaccording to a Skin Hydration Test set forth herein.

[0013] In another aspect, the present invention relates to a disposableabsorbent article which comprises an absorbent, a front waist section, arear waist section and an intermediate section which interconnects thefront and rear waist sections. The absorbent article defines a SkinHydration Value of less than about 18 grams per square meter per hourcalculated according to the Skin Hydration Test set forth herein. In aparticular embodiment, the absorbent article may define a Skin HydrationValue of less than about 15, desirably less than about 12 and moredesirably less than about 10 grams per square meter per hour calculatedaccording to the Skin Hydration Test. The absorbent article may furtherdefine a Wet Air Exchange Rate of at least about 190 cubic centimetersper minute and/or a Dry Air Exchange Rate of at least about 525 cubiccentimeters per minute calculated according to the Tracer Gas Test asset forth herein.

[0014] In another aspect, the present invention relates to a disposableabsorbent article which defines a front waist section, a rear waistsection, and an intermediate section which interconnects the front andrear waist sections. The absorbent article includes a) a vapor permeablebacksheet which defines a Water Vapor Transmission Rate of at leastabout 1000 grams per square meter per 24 hours calculated according to aWater Vapor Transmission Test as set forth herein; b) a liquid permeabletopsheet which is positioned in facing relation with the backsheet; andc) an absorbent body located between the backsheet and the topsheetwhich may define multiple zones of high air permeability for improvedair exchange. In a particular embodiment, the zones of high airpermeability in the absorbent body define a Frazier Porosity which is atleast about 10 percent greater than a Frazier Porosity of portions ofthe absorbent body adjacent to the zones of high air permeability. Theabsorbent article may further include a ventilation layer locatedbetween the backsheet and the absorbent body.

[0015] In still another aspect, the present invention relates to adisposable absorbent article which defines a front waist section, a rearwaist section, and an intermediate section which interconnects the frontand rear waist sections. The absorbent article includes a) a vaporpermeable, liquid impermeable backsheet which defines a Water VaporTransmission Rate of at least about 1000 grams per square meter per 24hours calculated according to a Water Vapor Transmission Test as setforth herein; b) a liquid permeable topsheet which is positioned infacing relation with the backsheet; c) an absorbent body located betweenthe backsheet and the topsheet; d) a ventilation layer located betweenthe backsheet and the absorbent body; and e) a surge management layerlocated between the topsheet and the absorbent body. In a particularembodiment, the absorbent body of the absorbent article includes aplurality of zones of high air permeability for improved air exchangewhich define a Frazier Porosity which is at least about 10 percentgreater than a Frazier Porosity of portions of the absorbent bodyadjacent to the zones.

[0016] In another aspect, the present invention relates to a disposableabsorbent article comprising an absorbent, a front waist section, a rearwaist section and an intermediate section which interconnects the frontand rear waist sections. The absorbent article defines a Wet AirExchange Rate/Dry Air Exchange Rate ratio of at least about 0.50calculated according to the Tracer Gas Test set forth herein.

[0017] In another aspect, the present invention relates to a disposableabsorbent article which comprises a vapor permeable backsheet whichdefines a Water Vapor Transmission Rate of at least about 1000 grams persquare meter per 24 hours calculated according to a Water VaporTransmission Test as set forth herein; a liquid permeable topsheet whichis positioned in facing relation with the backsheet; and an absorbentbody located between said backsheet and said topsheet. The absorbentarticle defines a Wet Air Exchange Rate/Dry Air Exchange Rate ratio ofat least about 1.00, desirably at least about 1.05 and more desirably atleast about 1.10 calculated according to a Tracer Gas Test set forthherein.

[0018] In yet another aspect, the present invention relates to adisposable absorbent article which defines a front waist section, a rearwaist section, and an intermediate section which interconnects the frontand rear waist sections. The absorbent article includes a vaporpermeable backsheet which defines a Water Vapor Transmission Rate of atleast about 1000 grams per square meter per 24 hours calculatedaccording to a Water Vapor Transmission Test as set forth herein; aliquid permeable topsheet which is positioned in facing relation withthe backsheet; and an absorbent body located between the backsheet andthe topsheet, wherein at least a portion of the absorbent body contractsin at least one of a machine direction and a cross machine direction atleast about 5 percent and desirably at least about 10 percent whensubjected to moisture vapor or moisture. In some embodiments, theabsorbent body includes a plurality of segments and the contraction ofthe absorbent body provides zones of high air permeability between thesegments.

[0019] In particular embodiments, the absorbent article defines a WetAir Exchange Rate/Dry Air Exchange Rate ratio of at least about 0.70,desirably at least about 0.80, more desirably at least about 0.90, evenmore desirably at least about 1.00 and even more desirably at leastabout 1.10.

[0020] In some embodiments, the absorbent article may also define a SkinHydration Value of less than about 18, desirably less than about 15,more desirably less than about 12, and even more desirably less thanabout 10 grams per square meter per hour calculated according to a SkinHydration Test set forth herein.

[0021] The absorbent article may further include a ventilation layerlocated between the backsheet and the absorbent body and or a surgemanagement layer between the topsheet and absorbent body for improvedair exchange.

[0022] The present invention advantageously provides improved absorbentarticles which exhibit increased breathability when wet which can leadto substantially reduced levels of hydration of the wearer's skin whenin use compared to conventional absorbent articles. The reduced level ofskin hydration promotes drier, more comfortable skin and renders theskin less susceptible to the viability of microorganisms. Thus, wearer'sof absorbent articles made according to the present invention havereduced skin hydration and more constant skin temperatures in use whichcan lead to a reduction in the incidence of skin irritation and rash andimproved skin health.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention will be more fully understood and furtheradvantages will become apparent when reference is made to the followingdetailed description of the invention and the accompanying drawings, inwhich:

[0024]FIG. 1 representatively shows a partially cutaway, top plan viewof an absorbent article according to one embodiment of the invention;

[0025]FIG. 2 representatively shows a sectional view of the absorbentarticle of FIG. 1 taken along line 2—2.

[0026]FIG. 3 representatively shows a partially cutaway, top plan viewof an absorbent body for an absorbent article according to anotherembodiment of the invention;

[0027]FIG. 4 representatively shows a sectional view of the absorbentbody of FIG. 3 taken along line 4—4.

[0028]FIG. 5 representatively shows a partially cutaway, top plan viewof an absorbent body for an absorbent article according to anotherembodiment of the invention;

[0029]FIG. 6 representatively shows a sectional view of the absorbentbody of FIG. 5 taken along line 6—6; and

[0030]FIG. 7 representatively shows a graph of the data from Example 15and Comparative Example 6.

DETAILED DESCRIPTION OF THE INVENTION

[0031] The following detailed description will be made in the context ofa disposable diaper article which is adapted to be worn by infants aboutthe lower torso. It is readily apparent, however, that the absorbentarticle of the present invention would also be suitable for use as othertypes of absorbent articles, such as feminine care pads, incontinencegarments, training pants, and the like.

[0032] The absorbent articles of the present invention advantageouslyexhibit increased breathability when wet which provides a substantiallyreduced level of hydration of the wearer's skin in use when compared toconventional absorbent articles. The absorbent articles of the presentinvention may further maintain a more constant temperature of thewearer's skin when wet when compared to conventional absorbent articles.Thus, wearer's of absorbent articles of the different aspects of thepresent invention have reduced skin hydration which renders the skinless susceptible to the viability of microorganisms which can lead to areduction in the incidence of skin irritation and rash. It has beendiscovered that the ability of the absorbent articles of the presentinvention to exhibit a low level of hydration on the wearer's skinduring use depends, at least in part, on the ability of the absorbentarticle to achieve a high rate of air exchange within the article.Moreover, it has been further discovered that the achievement of suchlow levels of skin hydration further depends on the ability of thearticle to maintain or increase the high rate of air exchange when wet.

[0033] The ability of an absorbent article to achieve high rates of airexchange both when dry and when wet has, for the purposes of thisapplication, been quantified as the Dry Air Exchange Rate, the Wet AirExchange Rate and the Wet Air Exchange Rate/Dry Air Exchange Rate ratioas determined according to the Tracer Gas Test set forth below. Briefly,the Tracer Gas Test involves injecting a tracer gas at a constant rateinside the absorbent article next to the skin of the wearer while thearticle is being worn. Simultaneously, the concentration of the tracergas in the air space between the article and the wearer is measured bywithdrawing a sample at the same constant rate as the injection. The airexchange is then determined based on mass balances of the tracer gas andthe air within the space in question.

[0034] To achieve the desired low levels of skin hydration, theabsorbent articles of the different aspects of the present invention maybe constructed to define a Wet Air Exchange Rate of at least about 190cubic centimeters per minute, generally at least about 200 cubiccentimeters per minute, desirably at least about 225 cubic centimetersper minute, more desirably at least about 250 cubic centimeters perminute, and even more desirably at least about 300 cubic centimeters perminute. For example, the absorbent articles may define a Wet AirExchange Rate of from about 175 to about 1500 cubic centimeters perminute and desirably from about 225 to about 1500 cubic centimeters perminute. Absorbent articles which exhibit Wet Air Exchange Rates lessthan those above do not allow a sufficient amount of air exchange andundesirably result in increased levels of skin hydration. Such increasedlevels of skin hydration can render the skin more susceptible to theviability of microorganisms which can undesirably lead to an increase inthe incidence of skin irritation and rash.

[0035] The absorbent articles of the different aspects of the presentinvention may be further constructed to define a Wet Air ExchangeRate/Dry Air Exchange Rate ratio of at least about 0.20, generally atleast about 0.23, desirably at least about 0.27, and more desirably atleast about 0.30 for improved performance. In particular embodiments,the absorbent articles of the different aspects of the present inventionare constructed to define a Wet Air Exchange Rate/Dry Air Exchange Rateratio of at least about 0.50, generally at least about 0.70, desirablyat least about 0.80, and more desirably at least about 0.90 for improvedperformance. In other particular embodiments, the absorbent articles ofthe different aspects of the present invention are constructed to definea Wet Air Exchange Rate/Dry Air Exchange Rate ratio of at least about1.00, generally at least about 1.05, and desirably at least about 1.10for improved performance. For example, the absorbent articles may definea Wet Air Exchange Rate/Dry Air Exchange Rate ratio of from about 0.20to about 2.00, desirably from about 0.50 to about 2.00, more desirablyfrom about 0.70 to about 2.00, and even more desirably from about 1.00to about 2.00 for improved performance. Absorbent articles which definesuch high Wet Air Exchange Rate/Dry Air Exchange Rate ratios provide theimproved air exchange when it is needed the most, i.e. when the articleis wetted.

[0036] The absorbent articles of the different aspects of the presentinvention may further be constructed to define a Dry Air Exchange Rateof at least about 525 cubic centimeters per minute, generally at leastabout 575 cubic centimeters per minute, desirably at least about 625cubic centimeters per minute, more desirably at least about 675 cubiccentimeters per minute, and even more desirably at least about 750 cubiccentimeters per minute for improved performance. For example, theabsorbent articles may define a Dry Air Exchange Rate of from about 525to about 2500 cubic centimeters per minute and desirably from about 575to about 2500 cubic centimeters per minute. Absorbent articles whichexhibit Dry Air Exchange Rates less than those above do not allow asufficient amount of air exchange and undesirably result in increasedlevels of skin hydration. Such increased levels of skin hydration canrender the skin more susceptible to the growth of microorganisms whichcan undesirably lead to an increase in the incidence of skin irritationand rash.

[0037] Alternatively, in embodiments wherein the absorbent articledefines a relatively high Wet Air Exchange Rate/Dry Air Exchange Rateratio it may not be necessary for such article to provide Dry AirExchange Rates set forth above to achieve improved performance. Forexample, in embodiments wherein the absorbent article defines a Wet AirExchange Rate/Dry Air Exchange Rate ratio of at least about 0.50,desirably at least about 0.70, more desirably at least about 0.80 andeven more desirably at least about 0.90, the absorbent article maydefine a Dry Air Exchange Rate of at least about 200, desirably at leastabout 225, more desirably at least about 250 and even more desirably atleast about 300 cubic centimeters per minute for improved performanceincluding reduced skin hydration and improved skin health.

[0038] The improved air exchange within the absorbent articles of thepresent invention has led to reduced skin temperature of the wearer inuse. The ability of an absorbent article to maintain a more constantskin temperature when wet has, for the purposes of this application,been quantified as the Wet Skin Temperature/Dry Skin Temperature ratioas determined according to the Skin Temperature Test set forth below.Briefly, the Skin Temperature Test involves placing the article to betested about the forearms of test participants and measuring thetemperature of the skin underneath the article before and after thearticle is wetted with a known amount of saline solution. The Dry SkinTemperature is recorded after the dry article has been worn for five (5)minutes. The article is then wetted and the Wet Skin Temperature isrecorded after the wetted article has been worn for one hundred twenty(120) minutes.

[0039] The absorbent articles of the different aspects of the presentinvention may be constructed to define Wet Skin Temperature/Dry SkinTemperature ratio of no more than about 1.010, generally no more thanabout 1.005, desirably no more than about 1.000, more desirably no morethan about 0.995, and even more desirably no more than about 0.990 forimproved performance. For example, the absorbent articles may define aWet Skin Temperature/Dry Skin Temperature ratio of from about 0.950 toabout 1.010 and desirably from about 0.970 to about 1.005 for improvedperformance. Absorbent articles which exhibit Wet Skin Temperature/DrySkin Temperature ratios greater than those above do not maintain skintemperature when wet which can render the skin more susceptible to theviability of microorganisms which can undesirably lead to an increase inthe incidence of skin irritation and rash.

[0040] The ability of the absorbent articles of the present invention toexhibit high levels of air exchange rate both when dry and when wet hasled to reduced levels of skin hydration. The ability of an absorbentarticle to achieve a low level of skin hydration has, for the purposesof this application, been quantified as the Skin Hydration Value. Asused herein, the term “Skin Hydration Value” refers to the valuedetermined according to the Skin Hydration Test set forth below. Ingeneral, the Skin Hydration Value is determined by measuring theevaporative water loss on the skin of test subjects after wearing thewetted absorbent article for a set period of time. In particularembodiments, the absorbent articles of the different aspects of thepresent invention may be constructed to define a Skin Hydration Value ofless than about 18 grams per square meter per hour, generally less thanabout 15 grams per square meter per hour, desirably less than about 12grams per square meter per hour, more desirably less than about 10 gramsper square meter per hour, even more desirably less than about 8 gramsper square meter per hour, and yet even more desirably less than about 5grams per square meter per hour for improved performance. For example,the absorbent articles of the present invention may define a SkinHydration Value of from about 0.1 to about 18 grams per square meter perhour and desirably from about 0.1 to about 12 grams per square meter perhour. Absorbent articles which exhibit Skin Hydration Values greaterthan those above can render the skin more susceptible to the growth ofmicroorganisms which can undesirably lead to an increase in theincidence of skin irritation and rash.

[0041] The improved wet and dry air exchange rates within the absorbentarticles of the present invention may further result in reducedviability rates of microorganisms which can lead to a reduction in skinirritation. It is hypothesized that the reduced viability ofmicroorganisms is a direct result of the increased breathability and airexchange within the articles of the present invention. The ability of anabsorbent article to achieve a low rate of viability of microorganismshas, for the purposes of this application, been quantified as the C.albicans viability value since it is hypothesized that the presence ofCandida albicans is directly related to the incidence of irritation and,in particular, rash. As used herein, the term “C. albicans viability”refers to the value determined according to the Candida albicansViability Test set forth below. The Candida albicans Viability Test, ingeneral, is a comparison of the C. albicans viability under a patch ofthe test absorbent article to the C. albicans viability under a controlpatch from a conventional absorbent article having a nonbreathable outercover, i.e. an outer cover having a WVTR of less than 100 grams persquare meter per 24 hours.

[0042] In particular embodiments, the absorbent articles of thedifferent aspects of the present invention may be constructed to definea C. albicans viability of less than about 85 percent, generally lessthan about 80 percent, desirably less than about 60 percent, moredesirably less than about 40 percent, and even more desirably less thanabout 20 percent of the C. albicans viability of the control forimproved performance. For example, the absorbent articles of the presentinvention may define a C. albicans viability of less than about 2.5,desirably less than about 2.0, and more desirably less than about 1.75log of C. albicans colony forming units when inoculated with asuspension of about 5-7 log of C. albicans colony forming unitsaccording to the Candida albicans Viability Test. Absorbent articleswhich exhibit C. albicans viability values greater than those above canundesirably lead to an increase in the incidence of skin irritation andrash.

[0043] Desirably, the above C. albicans viability values are obtainedwithout the incorporation of antimicrobial agents into the absorbentarticles which can be perceived by consumers in a negative manner.

[0044] It has been discovered that acceptable, improved performance ofabsorbent articles can be achieved by selecting constructions having acombination of one or more of the above-described properties. Forexample, a given level of acceptable, improved performance may beachieved by employing an absorbent article which exhibits a Wet AirExchange Rate of at least about 190 cubic centimeters per minute and aWet Air Exchange Rate/Dry Air Exchange Rate ratio of at least about 0.50and desirably at least about 1.00. Alternatively, acceptable, improvedperformance may be achieved by employing an absorbent article whichexhibits a Wet Air Exchange Rate/Dry Air Exchange Rate ratio of at leastabout 190 cubic centimeters per minute and a Skin Hydration Value ofless than about 18 grams per square meter per hour.

[0045] Still further, it has been discovered that improved performancecan be achieved by employing absorbent articles having a vapor permeablebacksheet which defines a WVTR of at least about 1000 grams per squaremeter per 24 hours and Wet Air Exchange Rate/Dry Air Exchange Rate ratioof at least about 0.50 and desirably at least about 1.00. Alternatively,acceptable, improved performance may be achieved by employing anabsorbent article having a vapor permeable backsheet which defines aWVTR of at least about 1000 grams per square meter per 24 hours and anabsorbent body, at least a portion of which contracts in one of amachine direction and a cross machine direction at least about 5 percentwhen subjected to moisture vapor or moisture.

[0046] Examples of suitable constructions of absorbent articles for usein the present invention are described below and representativelyillustrated in FIGS. 1-6. FIG. 1 is a representative plan view of anintegral absorbent garment article, such as disposable diaper 10, of thepresent invention in its flat-out, uncontracted state (i.e., with allelastic induced gathering and contraction removed). Portions of thestructure are partially cut away to more clearly show the interiorconstruction of diaper 10, and the surface of the diaper which contactsthe wearer is facing the viewer. FIG. 2 representatively shows asectional view of the absorbent article of FIG. 1 taken along line 2-2.With reference to FIGS. 1 and 2, the disposable diaper 10 generallydefines a front waist section 12, a rear waist section 14, and anintermediate section 16 which interconnects the front and rear waistsections. The front and rear waist sections include the general portionsof the article which are constructed to extend substantially over thewearer's front and rear abdominal regions, respectively, during use. Theintermediate section of the article includes the general portion of thearticle which is constructed to extend through the wearer's crotchregion between the legs.

[0047] The absorbent article includes a vapor permeable backsheet 20, aliquid permeable topsheet 22 positioned in facing relation with thebacksheet 20, and an absorbent body 24, such as an absorbent pad, whichis located between the backsheet 20 and the topsheet 22. The backsheet20 defines a length and a width which, in the illustrated embodiment,coincide with the length and width of the diaper 10. The absorbent body24 generally defines a length and width which are less than the lengthand width of the backsheet 20, respectively. Thus, marginal portions ofthe diaper 10, such as marginal sections of the backsheet 20, may extendpast the terminal edges of the absorbent body 24. In the illustratedembodiments, for example, the backsheet 20 extends outwardly beyond theterminal marginal edges of the absorbent body 24 to form side marginsand end margins of the diaper 10. The topsheet 22 is generallycoextensive with the backsheet 20 but may optionally cover an area whichis larger or smaller than the area of the backsheet 20, as desired. Thebacksheet 20 and topsheet 22 are intended to face the garment and bodyof the wearer, respectively, while in use.

[0048] The permeability of the backsheet is configured to enhance thebreathability of the absorbent article to reduce the hydration of thewearer's skin during use without allowing excessive condensation ofvapor, such as urine, on the garment facing surface of the backsheet 20which can undesirably dampen the wearer's clothes.

[0049] To provide improved fit and to help reduce leakage of bodyexudates from the diaper 10, the diaper side margins and end margins maybe elasticized with suitable elastic members, such as single or multiplestrands of elastic. The elastic strands may be composed of natural orsynthetic rubber and may optionally be heat shrinkable or heatelasticizable. For example, as representatively illustrated in FIGS. 1and 2, the diaper 10 may include leg elastics 26 which are constructedto operably gather and shirr the side margins of the diaper 10 toprovide elasticized leg bands which can closely fit around the legs ofthe wearer to reduce leakage and provide improved comfort andappearance. Similarly, waist elastics 28 can be employed to elasticizethe end margins of the diaper 10 to provide elasticized waists. Thewaist elastics are configured to operably gather and shirr the waistsections to provide a resilient, comfortably close fit around the waistof the wearer. In the illustrated embodiments, the elastic members areillustrated in their uncontracted, stretched condition for the purposeof clarity.

[0050] Fastening means, such as hook and loop fasteners 30, are employedto secure the diaper on a wearer. Alternatively, other fastening means,such as buttons, pins, snaps, adhesive tape fasteners, cohesives,mushroom-and-loop fasteners, or the like, may be employed.

[0051] The diaper 10 may further include other layers between theabsorbent body 24 and the topsheet 22 or backsheet 20. For example, asrepresentatively illustrated in FIGS. 1 and 2, the diaper 10 may includea ventilation layer 32 located between the absorbent body 24 and thebacksheet 20 to insulate the backsheet 20 from the absorbent body 24 toimprove air circulation and effectively reduce the dampness of thegarment facing surface of the backsheet 20. The ventilation layer 32 mayalso assist in distributing fluid exudates to portions of the absorbentbody 24 which do not directly receive the insult. The diaper 10 may alsoinclude a surge management layer 34 located between the topsheet 22 andthe absorbent body 24 to prevent pooling of the fluid exudates andfurther improve air exchange and distribution of the fluid exudateswithin the diaper 10.

[0052] The diaper 10 may be of various suitable shapes. For example, thediaper may have an overall rectangular shape, T-shape or anapproximately hour-glass shape. In the shown embodiment, the diaper 10has a generally I-shape. The diaper 10 further defines a longitudinaldirection 36 and a lateral direction 38. Other suitable diapercomponents which may be incorporated on absorbent articles of thepresent invention include containment flaps, waist flaps, elastomericside panels, and the like which are generally known to those skilled inthe art.

[0053] Examples of diaper configurations suitable for use in connectionwith the instant application which may include other diaper componentssuitable for use on diapers are described in U.S. Pat. No. 4,798,603issued Jan. 17, 1989, to Meyer et al.; U.S. Pat. No. 5,176,668 issuedJan. 5, 1993, to Bernardin; U.S. Pat. No. 5,176,672 issued Jan. 5, 1993,to Bruemmer et al.; U.S. Pat. No. 5,192,606 issued Mar. 9, 1993, toProxmire et al., and U.S. Pat. No. 5,509,915 issued Apr. 23, 1996 toHanson et al., the disclosures of which are herein incorporated byreference.

[0054] The various components of the diaper 10 are integrally assembledtogether employing various types of suitable attachment means, such asadhesive, sonic bonds, thermal bonds or combinations thereof. In theshown embodiment, for example, the topsheet 22 and backsheet 20 areassembled to each other and to the absorbent body 24 with lines ofadhesive, such as a hot melt, pressure-sensitive adhesive. Similarly,other diaper components, such as the elastic members 26 and 28,fastening members 30, and ventilation and surge layers 32 and 34 may beassembled into the diaper article by employing the above-identifiedattachment mechanisms.

[0055] The backsheet 20 of the diaper 10, as representativelyillustrated in FIGS. 1 and 2, is composed of a substantially vaporpermeable material. The backsheet 20 is generally constructed to bepermeable to at least water vapor and has a water vapor transmissionrate of at least about 1000 g/sq.m/24 hr., desirably at least about 1500g/sq.m/24 hr, more desirably at least about 2000 g/sq.m/24 hr., and evenmore desirably at least about 3000 g/sq.m/24. For example, the backsheet20 may define a water vapor transmission rate of from about 1000 toabout 6000 g/sq.m/24 hr. Materials which have a water vapor transmissionrate less than those above do not allow a sufficient amount of airexchange and undesirably result in increased levels of skin hydration.

[0056] The backsheet 20 is also desirably substantially liquidimpermeable. For example, the backsheet may be constructed to provide ahydrohead value of at least about 60 cm, desirably at least about 80 cm,and more desirably at least about 100 cm when subjected to theHydrostatic Pressure Test. Materials which have hydrohead values lessthan those above undesirably result in the strike through of liquids,such as urine, during use. Such fluid strike through can undesirablyresult in a damp, clammy feeling on the backsheet 20 during use.

[0057] The backsheet 20 may be composed of any suitable materials whicheither directly provide the above desired levels of liquidimpermeability and air permeability or, in the alternative, materialswhich can be modified or treated in some manner to provide such levels.In one embodiment, the backsheet 20 may be a nonwoven fibrous webconstructed to provide the required level of liquid impermeability. Forexample, a nonwoven web composed of spunbonded or meltblown polymerfibers may be selectively treated with a water repellent coating orlaminated with a liquid impermeable, vapor permeable polymer film toprovide the backsheet 20. In a particular embodiment of the invention,the backsheet 20 may comprise a nonwoven web composed of a plurality ofrandomly deposited hydrophobic thermoplastic meltblown fibers which aresufficiently bonded or otherwise connected to one another to provide asubstantially vapor permeable and substantially liquid impermeable web.The backsheet 20 may also comprise a vapor permeable nonwoven layerwhich has been partially coated or otherwise configured to provideliquid impermeability in selected areas.

[0058] Examples of suitable materials for the backsheet 20 are alsodescribed in U.S. Pat. No. 5,482,765 issued Jan. 9, 1996 in the name ofBradley et al. and entitled “NONWOVEN FABRIC LAMINATE WITH ENHANCEDBARRIER PROPERTIES”; U.S. patent application Ser. No. 08/622,903 filedMar. 29, 1996 in the name of Odorzynski et al. and entitled “ABSORBENTARTICLE HAVING A BREATHABILITY GRADIENT”; U.S. patent application Ser.No. 08/668,418 filed Jun. 21, 1996, in the name of Good et al. andentitled “ABSORBENT ARTICLE HAVING A COMPOSITE BREATHABLE BACKSHEET”;and U.S. patent application Ser. No. 08/882,712 filed Jun. 25, 1997, inthe name of McCormack et al. and entitled “LOW GAUGE FILMS ANDFILM/NONWOVEN LAMINATES”, the disclosures of which are hereinincorporated by reference.

[0059] In a particular embodiment, the backsheet 20 is provided by amicroporous film/nonwoven laminate material comprising a spunbondnonwoven material laminated to a microporous film. The spunbond nonwovencomprises filaments of about 1.8 denier extruded from a copolymer ofethylene with about 3.5 weight percent propylene and defines a basisweight of from about 17 to about 25 grams per square meter. The filmcomprises a cast coextruded film having calcium carbonate particlestherein and defines a basis weight of about 58 grams per square meterprior to stretching. The film is preheated, stretched and annealed toform the micropores and then laminated to the spunbond nonwoven. Theresulting microporous film/nonwoven laminate based material has a basisweight of from about 30 to about 60 grams per square meter and a watervapor transmission rate of from about 3000 to about 6000 g/sq.m/24 hr.Examples of such film/nonwoven laminate materials are described in moredetail in U.S. patent application Ser. No. 08/882,712 filed Jun. 25,1997, in the name of McCormack et al. and entitled “LOW GAUGE FILMS ANDFILM/NONWOVEN LAMINATES “, the disclosure of which has been incorporatedby reference.

[0060] The topsheet 22, as representatively illustrated in FIGS. 1 and2, suitably presents a bodyfacing surface which is compliant, softfeeling, and nonirritating to the wearer's skin. Further, the topsheet22 may be less hydrophilic than the absorbent body 24, to present arelatively dry surface to the wearer, and may be sufficiently porous tobe liquid permeable, permitting liquid to readily penetrate through itsthickness. A suitable topsheet 22 may be manufactured from a wideselection of web materials, such as porous foams, reticulated foams,apertured plastic films, natural fibers (for example, wood or cottonfibers), synthetic fibers (for example, polyester or polypropylenefibers), or a combination of natural and synthetic fibers. The topsheet22 is suitably employed to help isolate the wearer's skin from liquidsheld in the absorbent body 24.

[0061] Various woven and nonwoven fabrics can be used for the topsheet22. For example, the topsheet may be composed of a meltblown orspunbonded web of polyolefin fibers. The topsheet may also be abonded-carded web composed of natural and/or synthetic fibers. Thetopsheet may be composed of a substantially hydrophobic material, andthe hydrophobic material may, optionally, be treated with a surfactantor otherwise processed to impart a desired level of wettability andhydrophilicity. In a particular embodiment of the present invention, thetopsheet 22 comprises a nonwoven, spunbond, polypropylene fabriccomposed of about 2.8-3.2 denier fibers formed into a web having a basisweight of about 22 grams per square meter and a density of about 0.06gram per cubic centimeter. Such a topsheet 22 may be surface treatedwith an effective amount of a surfactant, such as about 0.3 weightpercent of a surfactant commercially available from Hodgson TextileChemicals Co. under the trade designation AHCOVEL BASE N-62.

[0062] The absorbent body 24 of the diaper 10, as representativelyillustrated in FIGS. 1 and 2, may suitably comprise a matrix ofhydrophilic fibers, such as a web of cellulosic fluff, mixed withparticles of a high-absorbency material commonly known as superabsorbentmaterial. In a particular embodiment, the absorbent body 24 comprises amatrix of cellulosic fluff, such as wood pulp fluff, and superabsorbenthydrogel-forming particles. The wood pulp fluff may be exchanged withsynthetic, polymeric, meltblown fibers or with a combination ofmeltblown fibers and natural fibers. The superabsorbent particles may besubstantially homogeneously mixed with the hydrophilic fibers or may benonuniformly mixed. Alternatively, the absorbent body 24 may comprise alaminate of fibrous webs and superabsorbent material or other suitablemeans of maintaining a superabsorbent material in a localized area.

[0063] The absorbent body 24 may have any of a number of shapes. Forexample, the absorbent core may be rectangular, I-shaped, or T-shaped.It is generally preferred that the absorbent body 24 be narrower in theintermediate section than in the front or rear waist sections of thediaper 10. The absorbent body 24 may be provided by a single layer or,in the alternative, may be provided by multiple layers, all of whichneed not extend the entire length and width of the absorbent body 24. Ina particular aspect of the invention, the absorbent body 24 can begenerally T-shaped with the laterally extending cross-bar of the “T”generally corresponding to the front waist section 12 of the absorbentarticle for improved performance, especially for male infants. In theillustrated embodiments, for example, the absorbent body 24 across thefront waist section 12 of the article has a cross-directional width ofabout 18 centimeters, the narrowest portion of the intermediate section16 has a width of about 7.5 centimeters and in the rear waist section 14has a width of about 11.4 centimeters.

[0064] The size and the absorbent capacity of absorbent body 24 shouldbe compatible with the size of the intended wearer and the liquidloading imparted by the intended use of the absorbent article. Further,the size and the absorbent capacity of the absorbent body 24 can bevaried to accommodate wearers ranging from infants through adults. Inaddition, it has been found that with the present invention, thedensities and/or basis weights of the absorbent body 24 can be varied.In a particular aspect of the invention, the absorbent body 24 has anabsorbent capacity of at least about 300 grams of synthetic urine.

[0065] In embodiments wherein the absorbent body 24 includes thecombination of hydrophilic fibers and high-absorbency particles, thehydrophilic fibers and high-absorbency particles can form an averagebasis weight for the absorbent body 24 which is within the range ofabout 400-900 grams per square meter. In certain aspects of theinvention, the average composite basis weight of such an absorbent body24 is within the range of about 500-800 grams per square meter, andpreferably is within the range of about 550-750 grams per square meterto provide the desired performance.

[0066] To provide the desired thinness dimension to the variousconfigurations of the absorbent article of the invention, the absorbentbody 24 can be configured with a bulk thickness which is not more thanabout 0.6 centimeters. Preferably, the bulk thickness is not more thanabout 0.53 centimeters, and more preferably is not more than about 0.5centimeters to provide improved benefits. The bulk thickness isdetermined under a restraining pressure of 0.2 psi (1.38 kPa).

[0067] The high-absorbency material can be selected from natural,synthetic, and modified natural polymers and materials. Thehigh-absorbency materials can be inorganic materials, such as silicagels, or organic compounds, such as crosslinked polymers. The term“crosslinked” refers to any means for effectively rendering normallywater-soluble materials substantially water insoluble but swellable.Such means can include, for example, physical entanglement, crystallinedomains, covalent bonds, ionic complexes and associations, hydrophilicassociations such as hydrogen bonding, and hydrophobic associations orVan der Waals forces.

[0068] Examples of synthetic, polymeric, high-absorbency materialsinclude the alkali metal and ammonium salts of poly(acrylic acid) andpoly(methacrylic acid), poly(acrylamides), poly(vinyl ethers), maleicanhydride copolymers with vinyl ethers and alpha-olefins, poly(vinylpyrrolidone), poly(vinyl morpholinone), poly(vinyl alcohol), andmixtures and copolymers thereof. Further polymers suitable for use inthe absorbent core include natural and modified natural polymers, suchas hydrolyzed acrylonitrile-grafted starch, acrylic acid grafted starch,methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, andthe natural gums, such as alginates, xanthum gum, locust bean gum, andthe like. Mixtures of natural and wholly or partially syntheticabsorbent polymers can also be useful in the present invention.

[0069] The high absorbency material may be in any of a wide variety ofgeometric forms. As a general rule, it is preferred that the highabsorbency material be in the form of discrete particles. However, thehigh absorbency material may also be in the form of fibers, flakes,rods, spheres, needles, or the like. In general, the high absorbencymaterial is present in the absorbent body in an amount of from about 1to about 90 weight percent, desirably in an amount of at least about 30weight percent, and even more desirably in an amount of at least about50 weight percent based on a total weight of the absorbent body 24. Forexample, in a particularly embodiment, the absorbent body 24 maycomprise a laminate which includes at least about 50 weight percent anddesirably at least about 70 weight percent of high-absorbency materialoverwrapped by a fibrous web or other suitable means of maintaining thehigh-absorbency material in a localized area.

[0070] An example of high-absorbency material suitable for use in thepresent invention is SANWET IM 3900 polymer available from HoechstCelanese, a business having offices in Portsmouth, Va. Other suitablesuperabsorbents may include FAVOR SXM 880 polymer obtained fromStockhausen, a business having offices in Greensboro, N.C.

[0071] Optionally, a substantially hydrophilic tissue wrapsheet (notillustrated) may be employed to help maintain the integrity of thestructure of the absorbent body 24. The tissue wrap sheet is typicallyplaced about the absorbent body over at least the two major facingsurfaces thereof and composed of an absorbent cellulosic material, suchas creped wadding or a high wet-strength tissue. In one aspect of theinvention, the tissue wrap can be configured to provide a wicking layerwhich helps to rapidly distribute liquid over the mass of absorbentfibers comprising the absorbent body.

[0072] The materials within the absorbent body 24 may further beconstructed to provide even higher levels of breathability when wet. Forexample, the absorbent body 24 may include materials which cause theabsorbent body 24 or at least a portion thereof to contract in the x-yplane, i.e. machine direction and/or cross machine direction, upon beingexposed to moisture or moisture vapor. As used herein, the term “machinedirection” refers to a direction in which the absorbent material ismoving as it is manufactured and the term “cross machine direction”refers to a direction perpendicular to the machine direction. Such acontractible absorbent body 24 or at least a portion thereof maycontract in one of the machine direction or cross machine direction or,desirably, the absorbent body 24 or at least a portion thereof contractsin both the machine direction and cross machine direction for improvedperformance. The contraction of the absorbent body 24 or at least aportion thereof will reduce the surface area of the absorbent body incontact with the backsheet and topsheet of the article thereby exposinga greater amount of the vapor permeable backsheet for improved airexchange within the article.

[0073] In a particular embodiment, the absorbent body 24 may includematerials which cause the absorbent body 24 or at least a portionthereof to contract in the machine direction and/or cross machinedirection upon being exposed to moisture vapor. The contraction of theabsorbent body 24 or portions thereof can be suitably controlled toprovide the desired increase in breathability when wet. For improvedperformance, the absorbent body 24 or at least a portion thereof maycontract at least about 5 percent, desirably at least about 10 percent,more desirably at least about 30 percent and even more desirably atleast about 50 percent in at least one of the machine direction or crossmachine direction when subjected to a relative humidity typically foundwithin an absorbent product, such as an infant diaper, during use. Forexample, the absorbent body 24 or at least a portion thereof maycontract from about 5 to about 80 percent and desirably from about 30 toabout 50 percent in at least one of the machine direction or crossmachine direction in use.

[0074] Such contractible absorbent materials can be incorporated intoabsorbent body 24 of the different aspects of the present invention in avariety of suitable manners. For example, the absorbent body 24 mayinclude a layer of the contractible absorbent material over or under alayer of conventional absorbent material having holes therein such that,upon exposure to moisture vapor, the contractible absorbent layercontracts thereby exposing holes in the conventional layer for improvedbreathability when wet. Alternatively, the absorbent body 24 may includea layer of the contractible absorbent material that has been segmentedsuch that, upon exposure to moisture vapor, the segments contractthereby creating more open area for improved air exchange. Suitablearrangements for the segments are discussed in more detail below.

[0075] In another embodiment, the absorbent body 24 may consist ofcontractile absorbent material including zones of high air permeability42 as described herein that upon exposure to moisture vapor increase insize as the remaining portions of the absorbent body contract to furtherincrease open area and improve air exchange. In yet another alternativeembodiment, the pieces of the contractible absorbent material may bemixed and formed with conventional absorbent such that, upon exposure tomoisture vapor, the contractible absorbent pieces contract to produceopen areas in the conventional absorbent structure. In anotheralternative embodiment, the absorbent body 24 may be selectively slitand attached to the absorbent article in such a manner that, uponexposure to moisture vapor, the contraction of the absorbent body 24causes the slits to widen and create more open area for improved airexchange without substantially affecting the overall dimensions of theabsorbent body 24.

[0076] Suitable materials for providing such contractible absorbentmaterials may include meltblown materials, coform materials, air-laidmaterials, bonded-carded web materials, hydroentangled materials,spunbond materials and the like and can comprise synthetic or naturalfibers.

[0077] In a particular embodiment, the contractible absorbent materialsin the absorbent body 24 include thermoplastic elastomeric polymerfibers. Materials suitable for use in preparing the thermoplasticelastomeric fibers herein include diblock, triblock, or multi-blockelastomeric copolymers such as olefinic copolymers, includingstyrene-isoprene-styrene, styrene-butadiene-styrene,styrene-ethylene/butylene-styrene, orstyrene-ethylene/propylene-styrene, which may be obtained from the ShellChemical Company, under the trade designation KRATON elastomeric resin;polyurethanes, including those available from E. I. Du Pont de NemoursCo., under the trade name LYCRA polyurethane; polyamides, includingpolyether block amides available from A to Chemical Company, under thetrade name PEBAX polyether block amide; polyesters, such as thoseavailable from E. I. Du Pont de Nemours Co., under the trade name HYTRELpolyester; and single-site or metallocene-catalzed polyolefins availablefrom Dow Chemical Co. under the trade name AFFINITY.

[0078] A number of block copolymers can be used to prepare thethermoplastic elastomeric fibers useful in this invention. Such blockcopolymers generally comprise an elastomeric midblock portion and athermoplastic endblock portion. The block copolymers used in thisinvention generally have a three-dimensional physical crosslinkedstructure below the endblock portion glass transition temperature (T₂)and are elastomeric. The block copolymers are also thermoplastic in thesense that they can be melted, formed, and resolidified several timeswith little or no change in physical properties (assuming a minimum ofoxidative degradation).

[0079] One way of synthesizing such block copolymers is to polymerizethe thermoplastic endblock portions separately from the elastomericmidblock portions. Once the midblock and endblock portions have beenseparately formed, they can be linked. Typically, midblock portions canbe obtained by polymerizing di- and tri-unsaturated C₄-C₁₀ hydrocarbonssuch as, for example, dienes such as butadiene, isoprene, and the like,and trienes such as 1,3,5-heptatriene, and the like. When an endblockportion A is joined to a midblock portion B, an A-B block copolymer unitis formed, which unit can be coupled by various techniques or withvarious coupling agents C to provide a structure such as A-B-A, which isbelieved to comprise two A-B blocks joined together in a tail-to-tailA-B-C-B-A arrangement. By a similar technique, a radial block copolymercan be formed having the formula (A-B)_(n) C, wherein is the hub orcentral polyfunctional coupling agent and n is a number greater than 2.Using the coupling agent technique, the functionality of C determinesthe number of A-B branches.

[0080] Endblock portion A generally comprises a poly(vinylarene), suchas polystyrene, having an average molecular weight between 1,000 and60,000. Midblock portion B generally comprises a substantially amorphouspolyolefin such as polyisoprene, ethylene/propylene polymers,ethylene/butylene polymers, polybutadiene, and the like, or mixturesthereof, having an average molecular weight between about 5,000 andabout 450,000. The total molecular weight of the block copolymer issuitably about 10,000 to about 500,000 and more suitably about 200,000to about 300,000. Any residual unsaturation in the midblock portion ofthe block copolymer can be hydrogenated selectively so that the contentof olefinic double bonds in the block copolymers can be reduced to aresidual proportion of less than 5 percent and suitably less than about2 percent. Such hydrogenation tends to reduce sensitivity to oxidativedegradation and may have beneficial effects upon elastomeric properties.

[0081] Suitable block copolymers used in this invention comprise atleast two substantially polystyrene endblock portions and at least onesubstantially ethylene/butylene mid-block portion. As an example,ethylene/butylene typically may comprise the major amount of therepeating units in such a block copolymer and can constitute, forexample, 70 percent by weight or more of the block copolymer. The blockcopolymer can have three or more arms, and good results can be obtainedwith, for example, four, five, or six arms. The midblock portion can behydrogenated, if desired. Linear block copolymers, such as A-B-A,A-B-A-B-A or the like, are suitably selected on the basis of endblockcontent, large endblocks being preferred. Forpolystyrene-ethylene/butylene-polystyrene block copolymers, a styrenecontent in excess of about 10 weight percent is suitable, such asbetween about 12 to about 30 weight percent. With higher styrenecontent, the polystyrene endblock portions generally have a relativelyhigh molecular weight. A commercially available example of such a linearblock copolymer is a styrene-ethylene/butylene-styrene block copolymerwhich contains about 13 weight percent styrene units and essentially thebalance being ethylene/butylene units, commercially available from theShell Chemical Company, under the trade designation KRATON G1657elastomeric resin. Typical properties of KRATON G1657 elastomeric resinare reported to include a tensile strength of 3400 pounds per squareinch (2×10⁶ kilograms per square meter), a 300 percent modulus of 350pounds per square inch (1.4×10⁵ kilograms per square meter), anelongation of 750 percent at break, a Shore A hardness of 65, and aBrookfield viscosity, when at a concentration of 25 weight percent in atoluene solution, of about 4200 centipoise at room temperature. Anothersuitable elastomer, KRATON G2740, is a styrene butadiene block copolymerblended with tackifier and low density polyethylene.

[0082] Other suitable elastomeric polymers may also be used to make thethermoplastic elastic fibers. These include, without limitation,elastomeric (single-site or metallocene catalyzed) polypropylene,polyethylene and other alpha-olefin homopolymers and copolymers;ethylene vinyl acetate copolymers; and substantially amorphouscopolymers and terpolymers of ethylene-propylene, butene-propylene, andethylene-propylene-butene.

[0083] Metallocene-catalyzed elastomeric polymers are relatively new,and are presently preferred. The metallocene process for makingpolyolefins uses a metallocene catalyst which is activated (i.e.ionized) by a co-catalyst.

[0084] Metallocene catalysts include bis(n-butylcyclopentadienyl)titanium dichloride, bis(n-butylcyclopentadienyl)zirconium dichloride,bis(cyclopentadienyl)scandium chloride, bis(indenyl)zirconiumdichloride, bis(methylcyclopentadienyl)titanium dichloride,bis(methylcyclopentadienyl)zirconium dichloride, cobaltocene,cyclopentadienyltitanium trichloride, ferrocene, hafnocene dichloride,isopropyl(cyclopentadienyl₁-1-flourenyl)zirconium dichloride,molybdocene dichloride, nickelocene, niobocene dichloride, ruthenocene,titanocene dichloride, zirconocene chloride hydride, zirconocenedichloride, among others. A more exhaustive list of such compounds isincluded in U.S. Pat. No. 5,374,696 to Rosen et al. and assigned to theDow Chemical Company. Such compounds are also discussed in U.S. Pat. No.5,064,802 to Stevens et al. and also assigned to Dow.

[0085] The metallocene process, and particularly the catalysts andcatalyst support systems are the subject of a number of patents. U.S.Pat. No. 4,542,199 to Kaminsky et al. describes a procedure wherein ametallocene catalyst of the general formula (cyclopentadienyl)2MeRHalwherein Me is a transition metal, Hal is a halogen and R iscyclopentadienyl or a C1 to C6 alkyl radical or a halogen, is used toform polyethylene. U.S. Pat. No. 5,189,192 to LaPointe et al. andassigned to Dow Chemical describes a process for preparing additionpolymerization catalysts via metal center oxidation. U.S. Pat. No.5,352,749 to Exxon Chemical Patents, Inc. describes a method forpolymerizing monomers in fluidized beds. U.S. Pat. No. 5,349,100describes chiral metallocene compounds and preparation thereof bycreation of a chiral center by enantioselective hydride transfer.

[0086] Co-catalysts are materials such as methylaluminoxane (MAO) whichis the most common, other alkylaluminums and boron containing compoundslike tris(pentafluorophenyl)boron, lithiumtetrakis(pentafluorophenyl)boron, and dimethylaniliniumtetrakis(pentafluorophenyl)boron. Research is continuing on otherco-catalyst systems or the possibility of minimizing or even eliminatingthe alkylaluminums because of handling and product contamination issues.The important point is that the metallocene catalyst be activated orionized to a cationic form for reaction with the monomer(s) to bepolymerized.

[0087] Polymers produced using metallocene catalysts have a narrowmolecular weight distribution. “Narrow molecular weight distributionpolymer” refers to a polymer that exhibits a molecular weightdistribution of less than about 3.5. As is known in the art, themolecular weight distribution of a polymer is the ratio of the weightaverage molecular weight of the polymer to the number average molecularweight of the polymer. Methods of determining molecular weightdistribution are described in the Encyclopedia of Polymer Science andEngineering, Volume 3, pages 299-300 (1985). Examples of narrowmolecular weight distribution polyolefins include themetallocene-catalyzed polyolefins, the single-site catalyzedpolyolefins, and the constrained geometry-catalyzed polyolefinsdescribed above. As is known in the art, the metallocene-catalyzedpolyolefins and the constrained geometry-catalyzed polyolefins aresometimes referred to as types of single-site catalyzed polymers.Polydispersities (Mw/Mn) of below 4 and as even below 2 are possible formetallocene produced polymers. These polymers also have a narrow shortchain branching distribution when compared to otherwise similarZiegler-Natta produced polymers.

[0088] It is also possible using a metallocene catalyst system tocontrol the isotacticity of the polymer quite closely when stereoselective metallocene catalysts are employed. In fact, polymers havebeen produced having an isotacticity of in excess of 99 percent. It isalso possible to produce highly syndiotactic polypropylene using thissystem.

[0089] Controlling the isotacticity of a polymer can also result in theproduction of a polymer which contains blocks of isotactic and blocks ofatactic material alternating over the length of the polymer chain. Thisconstruction results in an elastic polymer by virtue of the atacticportion. Such polymer synthesis is discussed in the journal Science,vol. 267 (Jan. 13, 1995) at p. 191 in an article by K. B. Wagner.Wagner, in discussing the work of Coates and Waymouth, explains that thecatalyst oscillates between the stereochemical forms resulting in apolymer chain having running lengths of isotactic stereocentersconnected to running lengths of atactic centers. Isotactic dominance isreduced producing elasticity. Geoffrey W. Coates and Robert M. Waymouth,in an article entitled “Oscillating Stereocontrol: A Strategy for theSynthesis of Thermoplastic Elastomeric Polypropylene” at page 217 in thesame issue, discuss their work in which they used metallocenebis(2-phenylindenyl)-zirconium dichloride in the presence ofmethylaluminoxane (MAO), and, by varying the pressure and temperature inthe reactor, oscillate the polymer form between isotactic and atactic.

[0090] Commercial production of metallocene polymers is somewhat limitedbut growing. Such polymers are available from Exxon Chemical Company ofBaytown, Tex. under the trade name EXXPOL for polypropylene basedpolymers and EXACT for polyethylene based polymers. Dow Chemical Companyof Midland, Mich. has polymers commercially available under the nameENGAGE. These materials are believed to be produced using non-stereoselective metallocene catalysts. Exxon generally refers to theirmetallocene catalyst technology as “single site” catalysts while Dowrefers to theirs as “constrained geometry” catalysts under the nameINSIGHT to distinguish them from traditional Ziegler-Natta catalystswhich have multiple reaction sites. Other manufacturers such as FinaOil, BASF, Amoco, Hoechst and Mobil are active in this area and it isbelieved that the availability of polymers produced according to thistechnology will grow substantially in the next decade.

[0091] Regarding metallocene based elastomeric polymers, U.S. Pat. No.5,204,429 to Kaminsky et al. describes a process which may produceelastic copolymers from cycloolefins and linear olefins using a catalystwhich is a stereorigid chiral metallocene transition metal compound andan aluminoxane. The polymerization is carried out in an inert solventsuch as an aliphatic or cycloaliphatic hydrocarbon such as toluene. Thereaction may also occur in the gas phase using the monomers to bepolymerized as the solvent. U.S. Pat. No. 5,278,272 and 5,272,236, bothto Lai et al., assigned to Dow Chemical and entitled “ElasticSubstantially Linear Olefin Polymers” describe polymers havingparticular elastic properties. Dow also commercially produces a line ofelastomeric polyolefins under the trade name ENGAGE. The elastomericfibers may be substantially continuous or staple in length, but arepreferably substantially continuous. Substantially continuous filamentsexhibit better containment of the cellulose fibers and superabsorbentmaterial, and provide better distribution of liquids, than staple lengthfibers. The elastomeric fibers may be produced using a spunbondingprocess, a meltblowing process, or another suitable process. Theelastomeric fibers may have an average diameter of about 1-75 microns,preferably about 1-40 microns, more preferably about 1-30 microns.

[0092] The thermoplastic elastomeric fibers may be circular but may alsohave other cross-sectional geometries such as elliptical, rectangular,triangular or multi-lobal. The thermoplastic elastomeric fibers may bewettable. The thermoplastic elastomeric fibers may be made wettable byfirst preparing the thermoplastic elastomeric fibers and thensubsequently applying a hydrophilizing surface treatment to the fibers.

[0093] Alternatively, the thermoplastic elastomeric fibers may be madewettable by adding a hydrophilic ingredient to the polymer prior tospinning. In general, any polymeric component capable of beingpolymerized with the thermoplastic elastomeric component, capable ofhydrophilizing the resultant copolymeric material to render it wettable,wherein the hydrophilizing component does not substantially affect theelastic properties of the prepared fiber, is suitable for use in thepresent invention. Hydrophilic ingredients suitable for use in thepresent invention include without limitation polyethylene oxide andpolyvinyl alcohol, as well as a wide variety of commercial hydrophilicsurfactants.

[0094] In still another embodiment, the thermoplastic elastomeric fibersmay be bicomponent or biconstituent filaments, in which one of thepolymer components is hydrophilic or rendered hydrophilic. An exemplaryembodiment is a sheath/core bicomponent filament having a hydrophiliccore surrounded by a hydrophilic sheath. Other additives such aspigments can also be included in the elastomeric filaments.

[0095] If the absorbent body 24 is a combination of elastomeric polymerfibers, high absorbency fibers and optionally other fibers such ascellulosic fibers, the relative percentages of the elastomeric polymerfibers and high absorbency fibers in the absorbent body 24 can vary overa wide range depending on the desired characteristics of the absorbentbody 24. For example, the absorbent body 24 may comprise from about 3 toabout 95 weight percent, desirably from about 5 to about 65 weightpercent, and more desirably from about 5 to about 50 weight percent ofelastomeric polymer fibers based on the dry weight of the absorbent body24. Such a combination of elastomeric polymer fibers and high absorbencyfibers may be manufactured by any method known to those skilled in theart.

[0096] In embodiments wherein the elastomeric polymer fibers aredispersed throughout the absorbent body 24, the absorbent body 24 can beformed by a coform process for a more uniform distribution of theelastomeric polymer fibers within the absorbent body 24. Such coformmaterials are manufactured generally as described in U.S. Pat. No.4,100,324 to Anderson et al. which issued Jul. 11, 1978; U.S. Pat. No.4,604,313 to McFarland et al. which issued Aug. 5, 1986; and U.S. Pat.No. 5,350,624 which issued Sep. 27, 1994; which are herein incorporatedby reference. Typically, such coform layers comprise a gas-formed matrixof elastomeric polymer fibers and other fibers, such as, for example,cellulose or high absorbency fibers. A coform absorbent is formed byinitially forming at least one primary air stream containing theelastomeric polymer fibers and merging the primary stream with at leastone secondary stream of other fibers. The primary and secondary streamsare merged under turbulent conditions to form an integrated streamcontaining a thorough, homogeneous distribution of the different fibers.The integrated air stream is directed onto a forming surface to air forma layer of material. One or more of these coform layers can then beformed in succession to provide a continuous web of coform absorbentmaterial. Such a process may also be used to provide discrete segmentsor portions which can be mixed and formed with conventional absorbentcores.

[0097] In a particular embodiment, the absorbent body 24 of theabsorbent articles of the present invention or at least a portionthereof includes a coform absorbent of elastomeric polymer fibers andhigh absorbent fibers wherein the elastomer to high absorbent fiberweight ratio is from about 3/97 to about 95/5. For example, theabsorbent body 24 or at least a portion thereof may include about 80weight percent high absorbent fibers commercially available fromTechnical Absorbents under the trade designation OASIS 101 and about 20weight percent elastomeric polymer fibers commercially available fromShell Chemical Company under the trade designation KRATON G2740. Suchcoform absorbent composites have exhibited up to a 50 percentcontraction in both the machine direction and cross machine directionwhen subjected to a relative humidity of at least 60 percent whichprovided a 75 percent reduction in surface area.

[0098] It is believed that the contraction of the above materials occursdue to the change in shape of the fibrous absorbent materials.Initially, these absorbents are a long cylindrical (fiber) shape, uponexposure to moisture vapor these fibrous materials contract into aglobular shapes which cause the system to contract. It should be notedthat the matrix material (previously referred to as the elastic resin)provides resistance to the contraction and by proper choice of materialsthe amount of contraction can be altered. The elastic polymers areparticularly suited to contraction since there is less resistance tothese forces. The contraction of the system could be varied by choice ofraw materials (matrix material and the fibrous absorbent) and the rawmaterial characteristics as well as the composition of the web.

[0099] In another embodiment, the contraction of the absorbent body 24is triggered by moisture, rather than moisture vapor. A method forachieving a moisture sensitive contractible absorbent material is toutilize a polymer matrix which is water sensitive. The material wouldinclude a polymer matrix as described above and a high absorbentmaterial such as superabsorbent particulates or fibers. A wide range ofmoisture sensitive polymers could be used. Suitable polymers willundergo a change in molecular conformation from an extended chain to acoil at the desired humidity level. This effect could optionally befurther enhanced and utilized in the formation of the contractilematerial by suitable processing techniques which would orient thepolymer chains in the desired direction and also by the degree ofcrystallization. Process aids as well as other additives to enhance themoisture responsive behavior of the polymers could also be optionallyused. Crosslinking of the polymer could also be used to achieve theoptimum combination of moisture responsive behavior and mechanicalproperties.

[0100] A wide range of polymers exhibit this moisture sensitive behaviorand are well known to one skilled in the art. An example of a polymerwhich would be suitable for this purpose is polyacrylic acid and itscopolymers at various degrees of neutralization. Other moisturesensitive polymers which would be useful include synthetic and naturalpolymers and modified natural polymers. Examples of these includepolymers and copolymers of polyvinyl alcohol, polyacrylonitrile and itscopolymers at various degrees of hydrolysis, polymethacrylic acid,hydrophilic polyurethanes, and polyethylene oxide. Natural polymers andmodified natural polymers that can be used include hydroxypropylcellulose, carboxymethyl cellulose, guar gum and modfied guar gum,modified starch based polymers and chitosan and modified chitosan.Blends of these polymers could also be used. Such polymers can beincorporated into the absorbent body 24 of the different aspects of thepresent invention in a variety of suitable manners as described abovefor contractible absorbent materials that contract when exposed tomoisture vapor.

[0101] In a particular embodiment, the absorbent body 24 may includeboth moisture vapor and moisture sensitive materials as discussed forimproved performance.

[0102] Such a contractible absorbent body 24 may also provide improvedfit maintenance when wet by reducing or eliminating droop and sag of theabsorbent body 24 as exhibited by conventional absorbent cores.

[0103] To provide the improved breathability when wet, the materialswhich form the absorbent body 24 may be constructed to have a high rateof swelling in the z-direction or thickness of the absorbent body 24 toprovide a more open porous structure after being wetted. An example ofsuch material is a wet-formed composite as described in commonlyassigned U.S. Patent Application entitled “WET-FORMED COMPOSITE DEFININGLATENT VOIDS AND MACRO-CAVITIES” filed herewith in the name of Edens etal. (Attorney Docket No. 15,126), which is hereby incorporated byreference. In general, the wet-formed composite includes superabsorbentmaterial contained by interbonded fibers that define internal voids ormacro-cavities between the fibers. As used herein, the terms“wet-formed,” “wet-laid,” and the like refer to composites which areformed from a process in which fibers are dispersed in a liquiddispersion medium to form a slurry. The slurry is deposited on a formingsurface to form the composite by removal of at least a portion of thedispersion medium. Those skilled in the art are familiar with suchprocesses.

[0104] In its dry state, the wet-formed composite has a pore structuresuitable for absorbing fluids quickly. When the wet-formed composite isinsulted with fluid, that portion of the composite and, in particular,the superabsorbent material that is wetted swells and expands which, inturn, expands the internal voids or macro-cavities. This expansionincreases internal void volume and as a result the breathability of thecomposite. That portion of the structure which has not been wetted, i.e.the structure at and beyond the fluid front, remains in its unexpandedform, and therefore remains capable of absorbing liquid at a relativelyhigh rate. Thus the dry portion of the wet-formed composite acts to drawfluid to regions of the wet-formed composite that are increasinglyremote from the initial point of insult.

[0105] Suitable fibers and superabsorbent material for the wet-formedcomposite are described above as being suitable for the absorbent body24 in general. The superabsorbent material present in the wet-formedcomposites is swellable in the dispersion medium. As used herein, anabsorbent material will be considered to be swellable in the dispersionmedium when the absorbent material can absorb at least 20 times,specifically at least 50 times, more specifically at least 75,particularly at least 100 times, and more particularly at least 150times or more its weight in the dispersion medium when the absorbentmaterial is dispersed in an excess of the dispersion medium for a periodof one hour.

[0106] A variety of materials may be suitable for use as the dispersionmedium. Exemplary of suitable dispersion mediums are water, otheraqueous materials, and the like. For reasons such as availability andeconomy, water is the preferred dispersion medium. The fibers aresuitably present in the dispersion medium in an amount of from about0.005 to about 3.0 weight percent, specifically of from about 0.01 toabout 2.0 weight percent and, particularly from about 0.01 to about 1.0weight percent, based on total weight of the fibers and dispersionmedium. The dispersion medium may contain other additives known to thoseskilled in the art of papermaking. Other suitable additives include,without limitation, binders, viscosity modifiers, adhesives,wet-strength additives, pH control additives, flocculants, and the like,provided they do not deleteriously affect the formation or performanceproperties of the wet-formed composites.

[0107] The dried wet-formed composites comprise fibers in an amountgreater than about 90 dry weight percent, specifically greater thanabout 95 dry weight percent, and particularly greater than about 98 dryweight percent, but less than 100 dry weight percent based on totalweight of the fibers and absorbent material present in the wet-formedcomposite. The superabsorbent material is present in an amount of lessthan about 10 dry weight percent, specifically less than about 5 dryweight percent, and particularly less than about 2 dry weight percent,but more than 0 dry weight percent based on total weight of the fibersand superabsorbent material present in the wet-formed composite. Theamount of superabsorbent material is selected so that the wet-formedcomposite has macro-cavities to help contain absorbed fluid and improvebreathability, but does not significantly reduce production capacity byvirtue of the amount of water that must be removed from the swollensuperabsorbent material during drying.

[0108] The wet-formed composite may be formed by combining the fibers, adispersion medium for the fibers, and superabsorbent material thatswells in the dispersion medium; providing sufficient contact timebetween the superabsorbent material and dispersion medium so that thesuperabsorbent material swells prior to forming the wet-formedcomposite; forming the wet-formed composite; and drying the wet-formedcomposite so that the superabsorbent material shrinks a substantialamount thereby forming macro-cavities within the wet-formed composite.The wet-formed composite may also be densified to collapse themacro-cavities, thereby forming latent voids or macro-cavities withinthe wet-formed composite.

[0109] It is desired that the superabsorbent material be combined withthe slurry of fibers such is that the superabsorbent material absorbs atleast about 20 times its weight in the dispersion medium, specificallyat least about 50 times its weight in the dispersion medium, morespecifically at least about 75 times its weight in the dispersionmedium, particularly at least about 100 times its weight in thedispersion medium, and more particularly about 150 times its weight inthe dispersion medium before the wet-formed composite is dried.Suitably, the superabsorbent material swells to the above-recitedamounts before the wet-formed composite is formed. The superabsorbentmaterial may be added to the slurry of fibers such that thesuperabsorbent material is distributed relatively uniformly throughoutthe slurry prior to forming the wet-formed composite.

[0110] The dried wet-formed composites may have a basis weight of about600 grams per square meter or less, specifically of about 250 grams persquare meter or less, more specifically of about 150 grams per squaremeter or less, particularly of about 150 to 250 grams per square meter,and suitably less than about 100 grams per square meter, but more than40 grams per square meter. Basis weight is selected so that thecomposite provides acceptable performance at a given raw material cost.

[0111] If the dried wet-formed composite is densified, the compositesmay have a density of about 0.1 grams per cubic centimeter or greater,specifically of about 0.12 grams per cubic centimeter or greater, morespecifically of about 0.15 grams per cubic centimeter or greater, andparticularly from about 0.12 to about 0.15 grams per cubic centimeter,but less than about 0.3 grams per cubic centimeter. Density is selectedso that the internal pore structure of the dried, wet-formed compositeis suitable for wicking and distributing fluid throughout the composite.Density is also selected so that the dried, wet-formed composite helpsimpart softness and thinness to the product in which the wet-formedcomposite is incorporated.

[0112] Constructions of the absorbent body 24 utilizing materials suchas, for example, the contractible absorbent materials or wet-formedabsorbent composites set forth above can lead to absorbent articleshaving even greater air exchange rates when wet. For example, suchconfigurations may provide absorbent articles which define a Wet AirExchange Rate/Dry Air Exchange Rate ratio of at least about 0.50,generally at least about 0.70, desirably at least about 0.80, and moredesirably at least about 0.90 for improved performance. Desirably, theconstruction of the absorbent body and article of the different aspectsof the present invention provide absorbent articles which define a WetAir Exchange Rate/Dry Air Exchange Rate ratio of at least about 1.00,generally at least about 1.05, and desirably at least about 1.10 forimproved performance.

[0113] The absorbent body 24 of the different aspects of the presentinvention may further include a plurality of zones of high airpermeability which allow air and vapors to readily pass through theabsorbent body 24 and through the vapor permeable backsheet 20 out ofthe diaper 10 into ambient air. For example, as representativelyillustrated in FIGS. 1 and 2, the absorbent body 24 may include aplurality of air passageways 40 which provide the absorbent body 24 withthe zones or regions of high air permeability 42. In the illustratedembodiment, the portions of the absorbent body 24 adjacent the airpassageways 40 provide zones or regions of high absorption 44. The zonesof high air permeability 42 are designed to provide the maximum airexchange from the absorbent body 24 while the zones of high absorption44 are designed to receive and hold the majority of the body exudates.The absorbent body 24 may define any number of zones of high airpermeability 42 which provides the improved air exchange. Desirably, theabsorbent body 24 defines at least 3 and more desirably at least 5different zones of high air permeability 42 for improved performance.

[0114] The zones of high air permeability 42, such as the airpassageways 40 as representatively illustrated in FIGS. 1 and 2, areconfigured to enhance the breathability of the article to reduce thehydration of the wearer's skin during use without allowing excessivecondensation of vapor, such as urine, on the garment facing surface ofthe backsheet 20. Such condensation of vapor on the outer surface of thediaper 10 can undesirably dampen the wearer's clothes. The zones of highair permeability 42 are generally located in the area of the diaper overwhich air and vapor can transfer from the topsheet 22, through theabsorbent body 24 and any other intervening layer or layers of material,and out the vapor permeable backsheet 20. For example, the zones of highair permeability 42 may be located throughout the entire absorbent body24 or may be selectively located in those regions of the absorbent body24 which provide the maximum air exchange, such as the intermediatesection 16 of the diaper 20. In a particular embodiment, the zones ofhigh air permeability 42 are located in the front and intermediatesections 12 and 16, respectively, of the diaper 10 for improved airexchange.

[0115] The zones of high absorption 44, on the other hand, are notdesigned to transfer a high level of air and vapor from the interior ofthe diaper. Thus, the air exchange from the topsheet 22 of the diaper 10to the backsheet 20 of the diaper and into the ambient atmosphere(exterior of the diaper) occurs generally through the absorbent body 24in the zones of high air permeability 42. Some air exchange through theabsorbent body 24 can also occur in the zones of high absorption 44 to alimited degree.

[0116] The zones of high air permeability may have any desiredconfiguration including rectangular, circular, hourglass, oval, and thelike, and may also include selected longitudinal or lateral strips ormultiple regions which may be intermittently located. For example, inFIGS. 1 and 2, the zones of high air permeability 42 are provided by aplurality of air passageways 40 or apertures through the absorbent body24 which have a generally circular configuration. In such aconfiguration, the zones of high absorption 44 comprise thenon-apertured portions of the absorbent body 24 between the airpassageways 40.

[0117] The zones of high air permeability 42 may have any desireddimensions which effectively provide improved air exchange whilepreventing excessive condensation of vapor from the absorbent body 24through and onto the garment facing surface of the backsheet 20.Desirably, the zones of high air permeability 42 may define a total areaof from about 5 to about 75 percent, more desirably at least about 10percent, even more desirably from about 10 to about 70 percent, andstill more desirably from about 10 to about 60 percent of the totalsurface area of the absorbent body 24 of the diaper 10.

[0118] For example, in a diaper intended for use on a medium sizedinfant, the zones of high air permeability 42 may define a total area offrom about 6 to about 90 square centimeters.

[0119] When the total area of the zones of high air permeability 42 isgreater than the above amounts, the diaper 10 may exhibit an undesirableamount of condensation of vapor on the exposed, garment facing surfaceof the backsheet 20 undesirably resulting in a clammy feeling on theouter surface of the diaper. Whereas, when the total area of the zonesof high air permeability 42 is less than the above amounts, the diaper10 may exhibit a low level of air exchange resulting in high levels ofskin hydration which can undesirably lead to skin irritation and rash.

[0120] The zones of high air permeability 42 of the absorbent body 24 ofthe diaper 10, as representatively illustrated in FIGS. 1 and 2, areconstructed to be substantially permeable to at least air and preferablypermeable to water vapor. For example, the zones of high airpermeability 42 of the absorbent body 24 define a Frazier Porosity valuewhich is at least about 10 percent, more desirably at least about 20percent and even more desirably at least about 50 percent greater thanthe Frazier Porosity value of the zones of high absorption 44 of theabsorbent body 24. As used herein, the term “Frazier Porosity” refers tothe value determined according to the Frazier Porosity Test set forthbelow. When the zones of high air permeability exhibit Frazier Porosityvalues less than those indicated above, the diaper 10 may exhibit a lowlevel of air exchange resulting in high levels of skin hydration whichcan undesirably lead to skin irritation and rash.

[0121] The zones of high air permeability may be provided in a varietyof ways. The zones of high air permeability 42 may be integral portionsof the absorbent body 24 of the absorbent article or may be provided byapertures, holes or open spaces in the absorbent body 24. For example,portions of the absorbent body 24 may be discontinuous or removed toprovide the zones 42. Alternatively, the zones of high air permeability42 may be provided by portions of the absorbent body 24 which areconstructed to absorb less fluid exudates thereby resulting in improvedair flow through such portions in use. For example, portions of theabsorbent body 24 may be void of or contain substantially lesshigh-absorbency material than other portions of the absorbent body 24 toprovide such improved air flow. Portions of the absorbent body 24 mayotherwise be treated or coated with a solution which renders themhydrophobic to provide the zones of high air permeability 42 in selectedareas. In other alternative configurations, the zones of high airpermeability 42 may be provided by creating voids or holes in theabsorbent body 24 and placing other materials having a higher airpermeability than the absorbent body 24, such as those materialsdescribed below as being suitable for the surge management layer 34, inthe holes or voids.

[0122] Examples of several configurations of the absorbent body 24according to different aspects of the present invention arerepresentatively illustrated in FIGS. 1-6. For example, in FIGS. 1 and2, the zones of high air permeability 42 in the absorbent body 24 areprovided by a plurality of air passageways 40 or apertures through theabsorbent body 24. In the illustrated embodiment, the air passageways 40are intermittently positioned along the entire length and width of theabsorbent body 24. The illustrated air passageways 40 are circular anddefine a diameter of about 1.27 centimeters and a total open area ofabout 12 percent of a total surface area of the absorbent body 24.

[0123] In FIGS. 3 and 4, the absorbent body 24 is in the form ofdiscrete segments 46 which are spaced apart along the longitudinaldirection 36 of the diaper 10. In such a configuration, the zones ofhigh air permeability 42 are provided by the spaces between the discretesegments 46 of the absorbent body 24. The absorbent body 24 may includeany number of segments 46 having a variety of shapes and sizes. Forexample, in the illustrated embodiment, the absorbent body 24 includesfour different segments 46 spaced apart in the longitudinal direction 36of the diaper 10. The illustrated segments 46 are generally rectangularin shape and define a width which is less than a width of the absorbentbody 24 which, in the illustrated embodiment, is defined by the width ofthe surge management layer 34 and the ventilation layer 32 as describedbelow.

[0124] Alternatively, the segments 46 may define a width which issubstantially equal to a width of the absorbent body 24. To assist inmaintaining the segments 46 in the spaced apart relationship, thesegments 46 can be contained between two sheets of material such aswrapsheet (not shown) or the surge management layer 34 and theventilation layer 32. In the illustrated embodiment, the segments 46include a laminate of high-absorbency material between two sheets orlayers of material and the zones of high air permeability 42 provided bythe spaces between the segments 46 define an open area of about 40percent of a total surface are of the absorbent body 24. In FIGS. 5 and6, the zones of high air permeability 42 in the absorbent body 24 areprovided by a plurality of air passageways 40 or apertures through theabsorbent body 24 similar to the embodiment illustrated in FIGS. 1 and2. However, in the embodiment illustrated in FIGS. 5 and 6, the airpassageways 40 are located in the absorbent body 24 in the front waistsection 12 and the intermediate section 16 of the diaper 10 and not inthe rear waist section 14. Moreover, in the embodiment illustrated inFIGS. 5 and 6, the absorbent body 24 includes an upper layer 48 and alower layer 50 with the upper layer 48 extending only along a portion ofthe length of the absorbent body 24. In such a configuration, themajority of the absorbent body 24 can be located in the front waist andintermediate sections 12 and 16 of the diaper 10 for improved absorptionand reduced cost. The illustrated air passageways 40 are circular anddefine a diameter of about 1.27 centimeters and a total open area ofabout 12 percent of a total surface area of the absorbent body 24.

[0125] Due to the thinness of absorbent body 24 and the high absorbencymaterial within the absorbent body 24, the liquid uptake rates of theabsorbent body 24, by itself, may be too low, or may not be adequatelysustained over multiple insults of liquid into the absorbent body 24. Toimprove the overall liquid uptake and air exchange, the diaper of thedifferent aspects of the present invention may further include a porous,liquid-permeable layer of surge management material 34, asrepresentatively illustrated in FIGS. 1 and 2. The surge managementlayer 34 is typically less hydrophilic than the absorbent body 24, andhas an operable level of density and basis weight to quickly collect andtemporarily hold liquid surges, to transport the liquid from its initialentrance point and to substantially completely release the liquid toother parts of the absorbent body 24. This configuration can helpprevent the liquid from pooling and collecting on the portion of theabsorbent garment positioned against the wearer's skin, thereby reducingthe feeling of wetness by the wearer. The structure of the surgemanagement layer 34 also generally enhances the air exchange within thediaper 10.

[0126] Various woven and nonwoven fabrics can be used to construct thesurge management layer 34. For example, the surge management layer 34may be a layer composed of a meltblown or spunbonded web of syntheticfibers, such as polyolefin fibers. The surge management layer 34 mayalso be a bonded-carded-web or an airlaid web composed of natural andsynthetic fibers. The bonded-carded-web may, for example, be a thermallybonded web which is bonded using low melt binder fibers, powder oradhesive. The webs can optionally include a mixture of different fibers.The surge management layer 34 may be composed of a substantiallyhydrophobic material, and the hydrophobic material may optionally betreated with a surfactant or otherwise processed to impart a desiredlevel of wettability and hydrophilicity. In a particular embodiment, thesurge management layer 34 includes a hydrophobic, nonwoven materialhaving a basis weight of from about 30 to about 120 grams per squaremeter.

[0127] For example, in a particular embodiment, the surge managementlayer 34 may comprise a bonded-carded-web, nonwoven fabric whichincludes bicomponent fibers and which defines an overall basis weight ofabout 83 grams per square meter. The surge management layer 34 in such aconfiguration can be a homogeneous blend composed of about 60 weightpercent polyethylene/polyester (PE/PET), sheath-core bicomponent fiberswhich have a fiber denier of about 3 d and about 40 weight percentsingle component polyester fibers which have a fiber denier of about 6 dand which have fiber lengths of from about 3.8 to about 5.08centimeters.

[0128] In the illustrated embodiments, the surge management layer 34 isarranged in a direct, contacting liquid communication with the absorbentbody 24. The surge management layer 34 may be operably connected to thetopsheet 22 with a conventional pattern of adhesive, such as a swirladhesive pattern. In addition, the surge management layer 34 may beoperably connected to the absorbent body 24 with a conventional patternof adhesive. The amount of adhesive add-on should be sufficient toprovide the desired levels of bonding, but should be low enough to avoidexcessively restricting the movement of liquid from the topsheet 22,through the surge management layer 34 and into the absorbent body 24.

[0129] The absorbent body 24 is positioned in liquid communication withsurge management layer 34 to receive liquids released from the surgemanagement layer, and to hold and store the liquid. In the shownembodiments, the surge management layer 34 comprises a separate layerwhich is positioned over another, separate layer comprising theabsorbent body 24, thereby forming a dual-layer arrangement. The surgemanagement layer 34 serves to quickly collect and temporarily holddischarged liquids, to transport such liquids from the point of initialcontact and spread the liquid to other parts of the surge managementlayer 34, and then to substantially completely release such liquids intothe layer or layers comprising the absorbent body 24.

[0130] The surge management layer 34 can be of any desired shape.Suitable shapes include for example, circular, rectangular, triangular,trapezoidal, oblong, dog-boned, hourglass-shaped, or oval. In certainembodiments, for example, the surge management layer can be generallyrectangular-shaped. In the illustrated embodiments, the surge managementlayer 34 is coextensive with the absorbent body 24. Alternatively, thesurge management layer 34 may extend over only a part of the absorbentbody 24. Where the surge management layer 34 extends only partiallyalong the length of the absorbent body 24, the surge management layer 34may be selectively positioned anywhere along the absorbent body 24. Forexample, the surge management layer 34 may function more efficientlywhen it is offset toward the front waist section 12 of the garment. Thesurge management layer 34 may also be approximately centered about thelongitudinal center line of the absorbent body 24.

[0131] Additional materials suitable for the surge management layer 34are set forth in U.S. Pat. No. 5,486,166 issued Jan. 23, 1996 in thename of C. Ellis et al. and entitled “FIBROUS NONWOVEN WEB SURGE LAYERFOR PERSONAL CARE ABSORBENT ARTICLES AND THE LIKE”; U.S. Pat. No.5,490,846 issued Feb. 13, 1996 in the name of Ellis et al. and entitled“IMPROVED SURGE MANAGEMENT FIBROUS NONWOVEN WEB FOR PERSONAL CAREABSORBENT ARTICLES AND THE LIKE”; and U.S. Pat. No. 5,364,382 issuedNov. 15, 1994 in the name of Latimer et al. and entitled “ABSORBENTSTRUCTURE HAVING IMPROVED FLUID SURGE MANAGEMENT AND PRODUCTINCORPORATING SAME”, the disclosures of which are hereby incorporated byreference.

[0132] As representatively illustrated in FIGS. 1 and 2, the diaper 10may also include a ventilation layer 32 located between the backsheet 20and the absorbent body 24. The ventilation layer 32 serves to facilitatethe movement of air within and through the diaper 10 and prevent thebacksheet 20 from being in surface to surface contact with at least aportion of the absorbent body 24. Specifically, the ventilation layer 32serves as a conduit through which air and water vapor can move from theabsorbent body 24 through the vapor permeable backsheet 20.

[0133] The ventilation layer 32 may be formed from materials describedabove as being suitable for the surge management layer 34 such asnonwoven, (e.g., spunbond, meltblown or carded), woven, or knittedfibrous webs composed of natural fibers and/or synthetic polymericfibers. Suitable fibers include, for example, acrylic fibers, polyolefinfibers, polyester fibers, or blends thereof. The ventilation layer 32may also be formed from a porous foam material such as an open-celledpolyolefin foam, a reticulated polyurethane foam, and the like. Theventilation layer 32 may include a single layer of material or acomposite of two or more layers of material. In a particular embodiment,the ventilation layer 32 includes a hydrophobic, nonwoven materialhaving a thickness of at least about 0.10 centimeters determined under arestraining pressure of 0.05 psi (0.34 kPa) and a basis weight of fromabout 20 to about 120 grams per square meter. For example, theventilation layer 32 may comprise a bonded-carded-web, nonwoven fabricwhich includes bicomponent fibers and which defines an overall basisweight of about 83 grams per square meter. The ventilation layer 32 insuch a configuration can be a homogeneous blend composed of about 60weight percent polyethylene/polyester (PE/PET), sheath-core bicomponentfibers which have a fiber denier of about 3 and about 40 weight percentsingle component polyester fibers which have a fiber denier of about 6and which have fiber lengths of from about 3.8 to about 5.08centimeters.

[0134] The ventilation layer 32 can be of any desired shape. Suitableshapes include for example, circular, rectangular, triangular,trapezoidal, oblong, dog-boned, hourglass-shaped, or oval. Theventilation layer 32 may extend beyond, completely over or partiallyover the absorbent body 24. For example, the ventilation layer 32 maysuitably be located over the intermediate section 16 of the diaper 10and be substantially centered side-to-side with respect to thelongitudinal centerline 36 of the diaper 10. It is generally desiredthat the entire absorbent body 24 be overlaid with the ventilation layer32 to prevent substantially all surface to surface contact between thebacksheet 20 and the absorbent body 24. In the illustrated embodiments,the ventilation layer 32 is coextensive with the absorbent body 24. Thisallows for the maximum degree of air exchange with minimal dampness onthe garment facing surface of the backsheet 20.

[0135] In the illustrated embodiments, the ventilation layer 32 isarranged in a direct, contacting liquid communication with the absorbentbody 24. The ventilation layer 32 may be operably connected to thebacksheet 20 with a conventional pattern of adhesive, such as a swirladhesive pattern. In addition, the ventilation layer 32 may be operablyconnected to the absorbent body 24 with a conventional pattern ofadhesive. The amount of adhesive add-on should be sufficient to providethe desired levels of bonding, but should be low enough to avoidexcessively restricting the movement of air and vapor from the absorbentbody 24 and through the backsheet 20.

[0136] The ventilation layer 32 may further serve to quickly collect andtemporarily hold discharged liquids, which pass through the absorbentbody 24 and, in particular, through the zones of high air permeability42 within the absorbent body 24. The ventilation layer 32 may thentransport such liquids from the point of initial contact and spread theliquid to other parts of the ventilation layer 32, and thensubstantially completely release such liquids into the layer or layerscomprising the absorbent body 24.

[0137] The different embodiments of the present invention, asrepresentatively illustrated in FIGS. 1-6, advantageously provideimproved absorbent articles which exhibit substantially reduced levelsof hydration of the wearer's skin when in use compared to conventionalabsorbent articles. The reduced levels of skin hydration promote drier,more comfortable skin and render the skin less susceptible to theviability of microorganisms. Thus, wearer's of absorbent articles madeaccording to the present invention have reduced skin hydration which canlead to a reduction in the incidence of skin irritation and rash.

[0138] Test Procedures

[0139] Hydrostatic Pressure Test

[0140] The Hydrostatic Pressure Test is a measure of the liquid barrierproperties of a material. In general, the Hydrostatic Pressure Testdetermines the height of water (in centimeters) in a column which thematerial will support before a predetermined amount of water passesthrough. A material with a higher hydrohead value indicates it is agreater barrier to liquid penetration than a material having a lowerhydrohead value. The Hydrostatic Pressure Test is performed according toMethod 5514—Federal Test Methods Standard No. 191A.

[0141] Frazier Porosity Test

[0142] The Frazier Porosity values referred to in the presentspecification can be determined employing a Frazier Air PermeabilityTester (Frazier Precision Instrument Co., Gaithersburg, Md.) and Method5450, Federal Test Methods Standard No. 191A. For the purposes of thepresent invention, the test is conducted with a sample which measures 8inches×8 inches.

[0143] Water Vapor Transmission Test

[0144] A suitable technique for determining the WVTR (water vaportransmission rate) value of a material is as follows. For the purposesof the present invention, 3-inch diameter (76 millimeter) circularsamples are cut from the test material and from a control material,Celguard® 2500 (Hoechst Celanese Corporation). Two or three samples areprepared for each material. Test cups used for testing are castaluminum, flanged, 2 inches deep and come with a mechanical seal andneoprene gasket. The cups are distributed by Thwing-Albert InstrumentCompany, Philadelphia, Pa., under the designation Vapometer cup #681.One hundred milliliters of distilled water are poured into eachVapometer cup, and each of the individual samples of the test materialsand control material are placed across the open top area of anindividual cup. Screw-on flanges are tightened to form a seal along theedges of the cups leaving the associated test material or controlmaterial exposed to the ambient atmosphere over a 62 millimeter diametercircular area (an open, exposed area of about 30 cm²). The cups are thenweighed, placed on a tray, and set in a forced air oven set at 100° F.(38° C.). The oven is a constant temperature oven with external aircirculating through it to prevent water vapor accumulation inside. Asuitable forced air oven is, for example, a Blue M Power-O-Matic 60 ovendistributed by Blue M Electric Co. of Blue Island, Ill. After 24 hours,the cups are removed from the oven and weighed. The preliminary, testWVTR value is calculated as follows:${{Test}\quad {WVTR}} = {\frac{\left\lbrack {\left( {{grams}\quad {weight}\quad {loss}\quad {over}\quad 24\quad {hours}} \right) \times 7571} \right\rbrack}{24}\quad \left( {g\text{/}m^{2}\text{/}24\quad {hours}} \right)}$

[0145] The relative humidity within the oven is not specificallycontrolled. Under predetermined set conditions of 100° F. and ambientrelative humidity, the WVTR for Celguard 2500 has been determined to be5000 g/m²124 hours. Accordingly, Celguard 2500 is run as a controlsample with each test. Celguard 2500 is a 0.0025 cm thick film composedof a microporous polypropylene.

[0146] Skin Hydration Test

[0147] Skin hydration values are determined by measuring totalevaporative water loss (EL) and can be determined by employing thefollowing test procedure.

[0148] The test is conducted on partially toilet trained infants whohave no lotions or ointments on the skin and have not been bathed within2 hours prior to the test. Each infant tests one diaper during each testsession. The test diapers include a test code and a control code. Thetest diapers (test code and control code) are randomized.

[0149] Each test diaper is weighed before and after use to verify thevolume of liquid added into the diaper. A felt tip pen is employed tomark an “X” at the target zone inside the diaper, with the “X”positioned 6.5 inches below the top front edge of the diaper andcentered side-to-side. The EL measurements are taken with anevaporimeter, such as an Evaporimeter EP1 instrument distributed byServomed AB, Stockholm, Sweden. Each test measurement is taken over aperiod of two minutes with EWL values taken once per second (a total of120 EWL values). The digital output from the Evaporimeter EP1 instrumentgives the rate of evaporative water loss (EWL) in g/m²/hr. Skinhydration values (SHV) are in units of total amount of water loss perunit area measured during the two-minute sampling period and arecalculated as follows.${{SHV}\quad \left( {g\text{/}m^{2}\text{/}{hour}} \right)} = \frac{\sum\limits_{n = 1}^{120}({EWL})_{n}}{120}$

[0150] A preliminary skin hydration value measurement is taken after a15-minute “dryout” period when the infant wears only a long T-shirt ordress and is in the supine position. The measurement is taken on theinfant's lower abdomen, in a region corresponding to the target zone ofthe diaper, using the evaporimeter for the purpose of establishing theinitial skin hydration value of the infant's skin at the diaper targetzone. If the preliminary SHV is less than 10 g/m²/hour, a diaper is thenplaced on the infant. If the preliminary SHV is greater than 10g/m²/hour, the “dryout” period is extended until a reading below 10g/m²/hour is obtained. Prior to securing the diaper on the infant, atube is positioned to direct a flow of liquid to hit the premarkedtarget zone. Once the diaper is secured, 210 milliliters of adjusted 0.9weight percent aqueous saline is added in three insults of 70milliliters each at a rate of 15 milliliters/second with a 45 seconddelay between insults.

[0151] The infant wears the diaper for 60 minutes after which the diaperis removed and a test measurement of skin hydration is taken on thelower abdomen corresponding to the target zone mark of the diaper. Themeasurement is taken over a 2-minute period. The used diaper is thenweighed. Relative humidity and temperature measurements can be takenwithin the diaper prior to the skin hydration measurements being taken.The test procedure is then repeated the next day for each infant usingthe diaper type (test or control) which the infant has not yet worn. Thecontrol diaper provides a standardized basis for comparing theperformance of the diaper configuration being tested and evaluated. Thecontrol diapers used in the tests performed in connection with theExamples were commercially available HUGGIES® Supreme diapers sold byKimberly-Clark Corporation.

[0152] Data is discarded for any infants which have added to the loadingof saline solution. The value reported for the mean net SHV (grams/m² inone hour) is the arithmetic mean for all infants of the post-wear skinhydration value, taken at the lower abdomen (target zone mark), minusthe skin hydration value measured at the lower abdomen prior to placingthe diaper on the infant (after “dryout” period). A separate mean netSHV is determined for the test code diapers and the control codediapers.

[0153] The net skin hydration value is determined as follows:

Net SHV _(i) =Y−Z

[0154] Where:

[0155] Y=skin hydration value measured at target zone mark of anindividual infant

[0156] Z=baseline skin hydration value measured on the lower abdomenafter “dryout” period prior to placing diaper on the infant

[0157] SHV_(i)=skin hydration value for individual infant

[0158] Then,${{Mean}\quad {Net}\quad {SHV}} = \frac{\sum\limits_{i = 1}^{N}{{Net}\quad {SHV}_{i}}}{N}$

[0159] Where: N=number of infants in study

[0160] The percent reduction in skin hydration is determined as follows:${\% \quad {Reduction}} = \frac{\sum\limits_{i = 1}^{N}\left\lbrack {\left( {\left( {C - D} \right)/C} \right) \times 100} \right\rbrack}{N}$

[0161] N

[0162] Where:

[0163] C=Net SHV_(i) for control diaper code

[0164] D=Net SHV_(i) for test diaper code

[0165] N=number of infants in study

[0166] Tracer Gas Test

[0167] The Tracer Gas Test is a measure of the rate of air exchange ingarments such as absorbent articles and is a steady flow/steady statetest described generally in TAPPI JOURNAL., Volume 80, No. 9, September1997. In general, the air exchange rate values are calculated from themeasured mass exchange within the garment. The test involves injecting atracer gas at a constant rate inside the article next to the outersurface of the torso of a mannequin while the article is secured aboutthe mannequin. Simultaneously, the concentration of the tracer gas inthe air space between the article and the mannequin is measured bywithdrawing a sample at the same constant rate as the injection. The airexchange rate is then be determined based on mass balances of the tracergas and the air within the space in question. The Tracer Gas Test iscompleted as follows:

[0168] Equipment

[0169] 1. Mannequin—The test is conducted with Step 3 or Step 4 sizeddiapers designed for infants weighing from about 16 to about 28 poundsand from about 22 to about 37 pounds, respectively. The diapers areplaced on mannequins which have the following dimensions: Step 3 height(waist to knees) 26 centimeters circumference at waist 42 centimeterscircumference at hips 44 centimeters thigh circumference 22 centimetersStep 4 height (waist to knees) 28 centimeters circumference at waist 48centimeters circumference at hips 51 centimeters thigh circumference 27centimeters

[0170] 2. A test area which is environmentally controlled to 20° C. and50% relative humidity.

[0171] 3. CO₂ Analyzer—An infrared CO₂ Analyzer such as Model 17515Acommercially available from Vacu-Med Vacumetrics, 4483 McGrath Street#102, Ventura, Calif.

[0172] 4. Rotameters—Rotameters to maintain gas flow rates such asMatheson Rotameter Model TS-35 commercially available from SpecialtyGases Southeast Inc., 3496 Peachtree Parkway, Suwanee, Ga.

[0173] 5. Gas Cylinders—Two gas cylinders of calibrated medical gradegas at a pressure of 4 kPa from Specialty Gases Southeast Inc., 3496Peachtree Parkway, Suwanee, Ga. The tracer gas includes 5% CO₂ and airand the calibration gas is 100% air.

[0174] Procedure

[0175] 1. Turn the CO₂ analyzer on. After it has been on for 30 minutes,calibrate the analyzer with the calibration gas and adjust the flowcontrol to achieve a flow rate of 150 cubic centimeters per minutethrough the analyzer.

[0176] 2. Place the diaper to be tested on the mannequin.

[0177] 3. Turn on the CO₂ tracer gas flow. The flow rate of the injectedtracer gas into the space between the diaper and the mannequin must beequal to the sample flow rate through the CO₂ analyzer (150 cc/min.).

[0178] 4. Measure and record the concentration (C) of the tracer gas(CO₂) in the air space between the diaper and the mannequin every 10seconds for 20 minutes. The data over the last 10 minutes are averagedand used to calculate the air exchange rate as follows:

Air Exchange Rate=150 cc/min*[(C _(T) −C)/(C−C _(O))]

[0179] wherein,

[0180] C_(T)=concentration of the tracer gas (5%)

[0181] C=concentration of the tracer gas in the space being measured

[0182] C_(O)=concentration of the tracer gas in the chamber environment(0.04%)

[0183] The Dry Air Exchange Rate is the air exchange rate as determinedaccording to the above procedure before the diaper has been subjected toany insults. The Wet Air Exchange Rate is the air exchange ratedetermined according to the above procedure except that once the diaperis secured to the mannequin, 180 milliliters (Step 3) or 210 milliliters(Step 4) of adjusted 0.9 weight percent aqueous saline is added in threeinsults of 60 or 70 milliliters each at a rate of 15 milliliters/secondwith a 45 second delay between insults. The Wet Air Exchange Rate/DryAir Exchange Rate ratio is determined by dividing the Wet Air ExchangeRate by the Dry Air Exchange Rate for the same sample.

[0184]C. albicans Viability Test

[0185] The C. albicans Viability Test is a measure of the effect ofabsorbent garments, such as disposable diapers, on the viability ofpathogenic microorganisms and, in particular, Candida albicans. Ingeneral, the C. albicans Viability Test involves inoculating delineatedsites of each volar forearm of test subjects with a known suspension ofC. albicans cells, covering the sites with full thickness patch from theabsorbent garment, and determining the viability after a 24 hour period.A full thickness test sample patch having a length of about 5centimeters and a width of about 5 centimeters is cut from the targetzone of each product to be tested. The target zone is generally thatportion of the product intended to receive urine discharge from thewearer and typically includes portions of the intermediate and frontwaist sections of the product somewhat forward of the lateral centerlineof the product. In a typical diaper configuration, the full thicknesstest sample patch includes the topsheet, absorbent body, backsheet andany intervening layers. Approximately 15 milliliters of a 0.9 weightpercent saline solution is added to the test sample patch and allowed tosoak in for 2 minutes before the samples are placed on the forearms ofthe test subjects. A test site area of about 6.15 square centimeters ismarked on each of the test subject's volar forearms. Approximately 0.01milliliters of a 0.9 weight percent saline solution containing a knownsuspension of C. albicans cells is delivered to the test site withmicropipettes and the suspension is then spread uniformly across thetest site. After air drying, the test site is covered with the testsample patch which is secured in position using adhesive tape completelysurrounding the sample.

[0186] After 24 hours, the test sample patches are removed and aquantitative culture is obtained from the test site using the detergentscrub method set forth in “A New Method For Quantitative Investigationof Cutaneous Bacteria”, P. Williamson and A. M. Klingman, Journal ofInvestigative Dermatology, 45:498-503, 1965, the disclosure of which ishereby incorporated by reference. Briefly, a sterile glass cylinderencompassing an area of 6.15 square centimeters is centered over thetest site and held firmly to the skin. One milliliter of 0.1 weightpercent Triton-x-100 in 0.075M phosphate buffer having a pH of 7.9 ispipetted into the glass cylinder and the area scrubbed for one minuteusing a sterile Teflon rod. The fluid is aspirated with a sterilepipette and a second milliliter of 0.1 weight percent Triton-x-100 in0.075M phosphate buffer having a pH of 7.9 is added to the glasscylinder. The scrub step is repeated and the two washes are pooled. Eachpooled sample is diluted in ten-fold steps with of 0.05 weight percentTriton-x-100 in 0.0375M phosphate buffer having a pH of 7.9. A 0.01milliliter aliquot of each dilution is inoculated onto Sabourands agarcontaining antibiotics. Duplicate cultures are prepared and incubated atroom temperature for 48 hours.

[0187] After incubation, the number of colony forming units are countedusing standard microbiological methods. The C. albicans viability undera patch of the test sample can then be compared to the C. albicansviability under a control patch from a conventional absorbent articlehaving a nonbreathable outer cover, i.e. an outer cover having a WVTR ofless than 100 grams per square meter per 24 hours, such as the diaperdescribed below in connection with Comparative Example 4.

[0188] Skin Temperature Test

[0189] Skin temperature values can be determined by employing thefollowing test procedure. The test is conducted on the bare forearm ofadult human beings who have no lotions, powders or ointments on the skinand have no skin disorders. The subjects also have not been bathed,swam, smoked, exercised or consumed caffeine within 2 hours prior to andduring the test. Each subject tests two articles such as diapers duringeach test session. The test diapers may include a test code and acontrol code such as the code identified in Comparative Example 6. Thetest diapers (test code and control code) are randomized and areconventional Step 3 sized diapers, i.e. for infants weighing 16-28pounds.

[0190] Each test diaper is weighed before and after use to verify thevolume of liquid added into the diaper. A pen is employed to mark a 1” X1” square at the target zone on the inside and outside of the diaper,with the center of the square positioned 6.0 inches below the top frontedge of the diaper and centered side-to-side. The temperature andhumidity measurements are taken with a temperature sensor, such as athermocouple probe with vinyl insulated 10-kt gold-plated disc sensordistributed by Cole-Parmer, a business having offices located in VernonHills, Ill. under the trade designation P-08506-80 which is attached toa Digi-Sense® Temperature/Humidity Logger distributed by Cole-Parmer, abusiness having office located in Vernon Hills, Ill. under the tradedesignation Model # 91090-00. The thermocouple probe is calibrated to apre-calibrated probe (3700-52) built into the data logger. The skintemperature measurements are taken continuously once per minute.

[0191] Upon arrival, each test subject is subjected to a 15 minuteacclimation period in a controlled environment at 40% relative humidityand 71° F. One temperature sensor is attached to each forearm,approximately midway between the wrist and elbow. The lead of the sensoris placed towards the elbow and the sensor is secured in place with apiece of tape such as Steri-Strip suture tape (0.25″×1.5″) commerciallyavailable from 3M on top of the sensor and another piece of tape to holdthe sensor lead in place. Baseline skin temperatures are recorded for aperiod of 5 minutes (5 minute total test time) without a diaper attachedto the forearm.

[0192] The sample diapers are then attached to respective forearms ofeach test subject such that the 1″×1″ target zones on the diaper arelocated over the temperature sensor. Prior to securing the diapers onthe forearms of the subject, a fluid dispenser nozzle, acclimated toroom temperature, is positioned in each diaper above the temperaturesensor to direct a flow of liquid to hit the premarked target zone. Eachdiaper does not overlap at the target zone and is secured in place byfastening masking tape which fastens the upper and lower portions of thediaper together without contacting the skin of the wearer. A size 3elastic stockinet retainer commercially available from Glenwood, Inc. isplaced over the entire diaper and forearm. Once the diapers are secured,dry diaper skin temperature is recorded for 5 minutes.

[0193] The diapers are then loaded with 180 milliliters of bodytemperature adjusted 0.9 weight percent aqueous saline is added in threeinsults of 60 milliliters each at a rate of 15 milliliters/second with a45 second delay between insults. The fluid dispenser nozzle is removedfrom each diaper. The subject wears each diaper for 120 additionalminutes while skin temperature readings are recorded every minute. Thediapers are then removed and weighed.

[0194] The value reported for the skin temperature is the arithmeticmean for all subjects at the specific time during the testing period foreach sample. The Wet Skin Temperature/Dry Skin Temperature ratio is thendetermined by dividing the skin temperature value after 120 minutes ofwearing the wetted sample (130 minute total test time) by the skintemperature value after 5 minutes of wearing the dry sample (10 minutetotal test time).

[0195] The following examples are presented to provide a more detailedunderstanding of the invention. The specific materials and parametersare exemplary and are not intended to specifically limit the scope ofthe invention.

EXAMPLES Example 1

[0196] Disposable diapers having the same general construction as theHUGGIES® Supreme Step 3 diapers described in connection with ComparativeExample 2 below were hand made and tested. The diapers weresubstantially the same as the Supreme diapers except that the backsheet,absorbent core, surge layer and elasticized legbands of the diapers werereplaced or modified and a ventilation layer was added between thebacksheet and the absorbent core.

[0197] In the tested diapers, the backsheet included a microporousfilm/nonwoven laminate material comprising a spunbond nonwoven materiallaminated to a microporous film. The spunbond nonwoven comprisedfilaments of about 1.8 denier extruded from a copolymer of ethylene withabout 3.5 weight percent propylene and defined a basis weight of fromabout 20 grams per square meter. The film comprised a cast coextrudedfilm having calcium carbonate particles therein and defined a basisweight of about 58 grams per square meter prior to stretching. The filmwas preheated, stretched and annealed to form the micropores and thenlaminated to the spunbond nonwoven material. The resulting microporousfilm/nonwoven laminate based material had a basis weight of 45 grams persquare meter and a water vapor transmission rate of about 4000 grams persquare meter per 24 hours. Examples of such film/nonwoven laminatematerials are described in more detail in U.S. patent application Ser.No. 08/882, 712 filed Jun. 25, 1997, in the name of McCormack et al. andentitled “LOW GAUGE FILMS AND FILM/NONWOVEN LAMINATES”, the disclosureof which has been incorporated by reference.

[0198] The absorbent core in the tested diapers was a dual layerabsorbent having the general configuration set forth in FIGS. 5 and 6except that there were no holes or apertures through either layer of theabsorbent. The absorbent core included an upper layer and a lower layerwith the upper layer extending from the front edge of the absorbent coreto a location about two thirds of the total length of the absorbentcore. The absorbent core included from about 10 to about 11 grams ofwood pulp fibers and from about 10 to about 11 grams of superabsorbentmaterial and, accordingly, included about 50 weight percent wood pulpfibers and about 50 weight percent superabsorbent material. The lowerlayer had a basis weight of about 230 grams per square meter and theupper layer had a basis weight of about 560 grams per square meter toprovide a total basis weight of about 790 grams per square meter in thefront section of the core and a basis weight of about 230 grams persquare meter in the back section of the core. The absorbent core furtherdefined a width in the crotch section of about 6.35 centimeters.

[0199] The surge layer was located between the absorbent core and thetopsheet and was the same material as the surge layer in the Supremediapers described in Comparative Example 2 except that it was modifiedto be coextensive with the absorbent core. The diapers also included aventilation layer between the absorbent core and the backsheet of thediaper. The ventilation layer was made of the same material as the surgelayer and was also coextensive with the absorbent core. The diapers alsoincluded an elasticized leg band assembly along about two thirds of thelength of each longitudinal side edge of the diaper. The assembly hadsix (6) strands of elastomeric material laminated to a breathable,nonwoven fabric layer. The elastic strands were composed of LYCRA®elastomer aligned along the longitudinal length of the diaper toelasticize and gather the diaper legbands.

[0200] Four samples of the diapers were subjected to the Tracer Gas Testset forth above. The results are set forth in Table 1 below.

Example 2

[0201] Disposable diapers having the same general construction as thediapers described in connection with Example 1 were hand made andtested. The diapers were substantially the same as the Example 1 diapersexcept that the absorbent body was modified to include a plurality ofholes therethrough in the region where the upper layer overlaid thelower layer as illustrated in FIGS. 5 and 6. The holes had a diameter of1.27 centimeters to provide an open area of about 12 percent based on atotal surface area of the absorbent body. Four samples of the diaperswere subjected to the Tracer Gas Test set forth above. The results areset forth in Table 1 below.

Example 3

[0202] Disposable diapers having the same general construction as thediapers described in connection with Example 2 were hand made andtested. The diapers were substantially the same as the Example 2 diapersexcept that the ventilation layer between the absorbent body and thebacksheet was removed. Four samples of the diapers were subjected to theTracer Gas Test set forth above. The results are set forth in Table 1below.

Example 4

[0203] Disposable diapers having the same general construction as thediapers described in connection with Example 2 were hand made andtested. The diapers were substantially the same as the Example 2 diapersexcept that the holes in the absorbent body had a diameter of 2.54centimeters which also defined an open are of about 12 percent of thetotal surface are of the absorbent body. Four samples of the diaperswere subjected to the Tracer Gas Test set forth above. The results areset forth in Table 1 below.

Example 5

[0204] Disposable diapers having the same general construction as thediapers described in connection with Example 2 were hand made andtested. The diapers were substantially the same as the Example 2 diapersexcept that the layered absorbent body was replaced with a non-layeredabsorbent body which included about 62 weight percent wood pulp fibersand about 38 weight percent superabsorbent and defined a basis weight inthe front section of about 750 to about 850 grams per square meter and abasis weight in the back section of about 375 to about 425 grams persquare meter. Four samples of the diapers were subjected to the TracerGas Test set forth above. The results are set forth in Table 1 below.

Example 6

[0205] Disposable diapers having the same general construction as thediapers described in connection with Example 2 were hand made andtested. The diapers were substantially the same as the Example 2 diapersexcept that the dual layered absorbent core was replaced with a laminatewhich included about 80 weight percent superabsorbent materialcommercially available from Stockhausen under the trade designationFAVOR SXM 880 overwrapped by a tissue layer of cellulosic fibers havinga basis weight of about 26 grams per square meter. The absorbent bodyalso included apertures therethrough having a diameter of 1.27centimeters to provide an open area of about 12 percent of the totalsurface area of the absorbent body. Four samples of the diapers weresubjected to the Tracer Gas Test set forth above. The results are setforth in Table 1 below.

Example 7

[0206] Disposable diapers having the same general construction as thediapers described in connection with Example 2 were hand made andtested. The diapers were substantially the same as the Example 2 diapersexcept that the absorbent body was replaced with a laminate whichincluded about 80 weight percent superabsorbent material commerciallyavailable from Stockhausen under the trade designation FAVOR SXM 880overwrapped by a tissue layer of cellulosic fibers having a basis weightof about 26 grams per square meter. The laminate was provided in foursegments as representatively illustrated in FIGS. 3 and 4 which resultedin an open area for the absorbent body of about 40 percent of a totalsurface area of the absorbent body. Four samples of the diapers weresubjected to the Tracer Gas Test set forth above. The results are setforth in Table 1 below.

Example 8

[0207] Disposable diapers having the same general construction as thediapers described in connection with Example 2 were hand made andtested. The diapers were substantially the same as the Example 2 diapersexcept that the backsheet was modified to define a water vaportransmission rate of about 1870 grams per square meter per 24 hours.Four samples of the diapers were subjected to the Tracer Gas Test setforth above. The results are set forth in Table 1 below.

Comparative Example 1

[0208] Disposable diapers having the same general construction as theSupreme Step 3 diapers as described in connection with Example 2 werehand made and tested. The diapers were substantially the same as theExample 2 diapers except that the backsheet was replaced with a 1 milthick polyethylene film material having a water vapor transmission rateof less than 100 grams per square meter per hour. Four samples of thediapers were subjected to the Tracer Gas Test set forth above. Theresults are set forth in Table 1 below.

Comparative Example 2

[0209] Disposable diapers having the same general construction as thosediapers commercially available from Kimberly-Clark Corporation under thetrade designation HUGGIES® Supreme Step 3 were tested.

[0210] In essence, the Supreme diapers comprised an absorbent coreconsisting of a mixture of wood pulp fibers and superabsorbent materialsurrounded by a two piece cellulosic wrap sheet having a basis weight ofabout 16-21 grams per square meter. The absorbent core included fromabout 12.5 to about 13.5 grams of airlaid wood pulp fibers and fromabout 7.0 to about 8.5 grams of superabsorbent material. Thesuperabsorbent material was purchased from Stockhausen under the tradedesignation FAVOR SXM 880. The superabsorbent material was homogeneouslymixed with the pulp fibers to form a unitary layer having a densitywithin the range of 0.25 to 0.35 grams per cubic centimeter. Thehomogeneous mixture of the superabsorbent material and the wood pulpfibers was zoned along the machine direction to provide a basis weightof from about 600 to about 700 grams per square meter in the frontsection of the absorbent core and a basis weight of from about 300 toabout 350 grams per square meter in the back section of the absorbentcore.

[0211] The Supreme diapers further included a composite backsheetcomprising a vapor-permeable barrier layer adhesively laminated to aspunbond/meltblown/spunbond laminate material (hereinafter “SMS”). TheSMS material had a basis weight of about 27 grams per square meter. Thevapor-permeable barrier layer consisted of a polyolefin film which had athickness of about 0.7 mil. and a basis weight of about 19.5 grams persquare meter. The polyolefin film material was commercially availablefrom Exxon Chemical Patents Incorporated, under the tradename EXXAIRE.The vapor-permeable barrier layer was adhered to the SMS laminate andpositioned between the absorbent core and the SMS laminate material ofthe backsheet. The backsheet had a water vapor transmission rate ofabout 1500 grams per square meter per 24 hours. The absorbent core wassandwiched between the backsheet and a topsheet composed of a spunbondweb of polypropylene fibers having a basis weight of about 17 grams persquare meter. A surge management layer composed of a bonded carded webwas located between the topsheet and the absorbent core. The surge layerincluded bicomponent fibers and defined an overall basis weight of about83 grams per square meter. The surge layer was a homogeneous blendcomposed of about 60 weight percent polyethylene/polyester (PE/PET),sheath-core bicomponent fibers which had a fiber denier of about 3 andabout 40 weight percent single component polyester fibers which had afiber denier of about 6 and which have fiber lengths of from about 3.8to about 5.08 centimeters. The surge layer further defined a width ofabout 10.2 centimeters and a length of about 16.5 centimeters. The frontedge of the surge layer was located 5.1 centimeters from the front edgeof the absorbent core.

[0212] The Supreme diapers further included a single componentelasticized waistband and waist flap assembly at each longitudinal endof the diaper. The assembly had multiple strands of elastomeric materialsandwiched and laminated between a polymer film layer and a nonwovenfabric layer. The polymer film was a 0.00075 inch thick film composed ofa blend of a linear low density polyethylene and an ultra low densitypolyethylene. The nonwoven fabric layer was composed of a 20 grams persquare meter web of polypropylene spunbond. The elastic strands werecomposed of about 8-16 strands of LYCRA® elastomer aligned along thecross-direction of the diaper to elasticize and gather the diaperwaistbands and the internal waist flaps. The Supreme diapers alsoincluded length-wise containment flaps which extend the full length ofthe diaper and elasticized leg bands along each longitudinal side edgeof the diaper. The elastic strands in the leg band and containment flapswere composed of LYCRA® elastomer aligned along the longitudinal lengthof the diaper to elasticize and gather the diaper legbands and thecontainment flaps.

[0213] Four samples of the diapers were subjected to the Tracer Gas Testset forth above. The results are set forth in Table 1 below. TABLE 1Mean Mean Dry Air Exc. Wet Air Exc. Wet/Dry Rate (cm³/min.) Rate(cm³/min.) Ratio Example 1 822 224 0.27 Example 2 794 310 0.39 Example 3679 220 0.32 Example 4 1050 360 0.34 Example 5 758 190 0.25 Example 6724 240 0.33 Example 7 677 153 0.23 Example 8 495 316 0.63 ComparativeEx. 1 51 110 2.16 Comparative Ex. 2 513 171 0.33

[0214] The test results from Examples 1-8 and Comparative Examples 1 and2 indicate that diapers made according to the present inventiongenerally have improved levels of air exchange both when dry and whenwet when compared to conventional diapers.

Example 9

[0215] Four samples of diapers having the same general construction asthe diapers described in connection with Example 2 were hand made andtested according to the Skin Hydration Test set forth above. The diaperswere substantially the same as the Example 2 diapers except that thediapers were similar in size to commercially available Step 4 sizediapers, the absorbent body was a single layer having the same thicknessthroughout, and the apertures had a diameter of 2.54 centimeters. Thediapers defined an average Skin Hydration Value of 8.1 grams per squaremeter per hour. The results are also set forth in Table 2 below.

Example 10

[0216] Four samples of diapers having the same general construction asthe diapers described in connection with Example 6 were hand made andtested according to the Skin Hydration Test set forth above. The diaperswere substantially the same as the Example 6 diapers except that thediapers were similar in size to commercially available Step 4 sizediapers, the absorbent body defined a basis weight of about 560 gramsper square meter and the apertures had a diameter of 2.54 centimeters.The diapers defined an average Skin Hydration Value of 2.8 grams persquare meter per hour. The results are also set forth in Table 2 below.

Example 11

[0217] Four samples of diapers having the same general construction asthe diapers described in connection with Example 7 were hand made andtested according to the Skin Hydration Test set forth above. The diaperswere substantially the same as the Example 7 diapers except that thediapers were similar in size to commercially available Step 4 sizediapers. The diapers defined an average Skin Hydration Value of 1.6grams per square meter per hour. The results are also set forth in Table2 below.

Comparative Example 3

[0218] Disposable diapers having the same general construction as thosediapers commercially available from Kimberly-Clark Corporation under thetrade designation HUGGIES® Supreme Step 4 were tested. In essence, theStep 4 sized Supreme diapers were similar to the Step 3 sized Supremediapers described above in connection with Comparative Example 2 exceptthat the size of the materials was greater.

[0219] Four samples of the diapers were subjected to the Skin HydrationTest set forth above. The diapers defined an average Skin HydrationValue of 19.3 grams per square meter per hour. The results are also setforth in Table 2 below. TABLE 2 Skin Hydration Value (g/m²/hr) Example 98.1 Example 10 2.8 Example 11 1.6 Comparative Ex. 3 19.3

[0220] The test results from Examples 9-11 and Comparative Example 3indicate that diapers made according to the teachings of the presentinvention exhibit significantly improved Skin Hydration Values whencompared to conventional diapers. Specifically, diapers made accordingto the present invention exhibited a 58 to 92 percent reduction in theSkin Hydration Value. While some reduction in the Skin Hydration Valuewas anticipated due to the increased amount of air exchange within thediapers, the magnitude of the reduction was unexpected.

Example 12

[0221] Samples of diapers having the same general construction as thediapers described in connection with Comparative Example 2 were handmade and tested. The diapers were substantially the same as theComparative Example 2 diapers except that the backsheet was modified todefine a water vapor transmission rate of about 3000 grams per squaremeter per 24 hours. The diapers were subjected to the C. albicansViability Test set forth above. The samples of Example 12 andComparative Example 4 (control) were tested on the volar forearms ofeach of seven test subjects. Approximately 0.01 milliliters of a 0.9weight percent saline solution containing a suspension of 5.71 log of C.albicans colony forming units was delivered to the test site withmicropipettes and the suspension was then spread uniformly across thetest site. The sample diapers according to this example defined a meanC. albicans viability of 1.96 log of C. albicans colony forming units.Accordingly, compared to the mean C. albicans viability of the control(Comparative Example 4), the diapers according to this example defined areduction in the C. albicans viability value of 26 percent.

Example 13

[0222] Samples of diapers having the same general construction as thediapers described in connection with Example 2 except that the backsheetdefines a water vapor transmission rate of about 5000 grams per squaremeter per 24 hours are made. The diapers are subjected to the C.albicans Viability Test set forth above. The samples of Example 13 andComparative Example 4 (control) are tested on the volar forearms of eachof seven test subjects. Approximately 0.01 milliliters of a 0.9 weightpercent saline solution containing a suspension of 5.71 log of C.albicans colony forming units is delivered to the test site withmicropipettes and the suspension is then spread uniformly across thetest site. It is anticipated that the sample diapers according to thisexample would define a mean C. albicans viability of more likely lessthan 1.75 and likely less than 1.50 log of C. albicans colony formingunits. Accordingly, compared to the mean C. albicans viability of thecontrol (Comparative Example 4), it is anticipated that the diapersaccording to this example will define a reduction in the C. albicansviability value of more likely about 34 percent and likely about 43percent.

Comparative Example 4

[0223] Samples of diapers having the same general construction as thediapers described in connection with Comparative Example 2 were handmade and tested. The diapers were substantially the same as theComparative Example 2 diapers except the backsheet was replaced with a1.0 mil thick polyethylene film material having a water vaportransmission rate of less than 100 grams per square meter per 24 hours.The diapers were subjected to the C. albicans Viability Test set forthabove on the volar forearms of each of seven test subjects.Approximately 0.01 milliliters of a 0.9 weight percent saline solutioncontaining a suspension of 5.71 log of C. albicans colony forming unitswas delivered to the test site with micropipettes and the suspension wasthen spread uniformly across the test site. The sample diapers accordingto this example defined a mean C. albicans viability of 2.65 log of C.albicans colony forming units.

Example 14

[0224] Samples of diapers having the same general construction as thediapers described in connection with Example 13 were machine made andtested. In particular, the backsheet of the diapers defined a watervapor transmission rate of about 5000 grams per square meter per 24hours. The diapers were subjected to the C. albicans Viability Test setforth above. The samples of Example 14 and Comparative Example 5(control) were tested on the volar forearms of each of twenty testsubjects. Approximately 0.01 milliliters of a 0.9 weight percent salinesolution containing a suspension of 4.92 log of C. albicans colonyforming units was delivered to the test site with micropipettes and thesuspension was then spread uniformly across the test site. The samplediapers according to this example defined a mean C. albicans viabilityof 1.26 log of C. albicans colony forming units. Accordingly, comparedto the mean C. albicans viability of the control (Comparative Example5), the diapers according to this example defined a reduction in the C.albicans viability value of 61 percent.

Comparative Example 5

[0225] Samples of diapers having the same general construction as thediapers described in connection with Comparative Example 4 were machinemade and tested. In particular, the backsheet of the diapers included a1.0 mil thick polyethylene film material having a water vaportransmission rate of less than 100 grams per square meter per 24 hours.The diapers were subjected to the C. albicans Viability Test set forthabove on the volar forearms of each of twenty test subjects.Approximately 0.01 milliliters of a 0.9 weight percent saline solutioncontaining a suspension of 4.92 log of C. albicans colony forming unitswas delivered to the test site with micropipettes and the suspension wasthen spread uniformly across the test site. The sample diapers accordingto this example defined a mean C. albicans viability of 3.26 log of C.albicans colony forming units.

[0226] The test results from Examples 12 and 14 and the expected resultsfrom Example 13 show that diapers made according to the presentinvention exhibit a reduced viability and incidence of microbialinfection when compared to conventional absorbent diapers and the testresults from Comparative Examples 4 and 5. It is clear that such reducedmicrobial viability is achieved by reducing the occlusion of the skin byincreasing the breathability of the diaper both when dry and when wet.

Example 15

[0227] Samples of diapers having the same general construction as thediapers described in connection with Example 2 except that the backsheetdefined a water vapor transmission rate of about 5000 grams per squaremeter per 24 hours were made. The diapers were subjected to the SkinTemperature Test set forth above. The samples were tested on one of theforearms of each of eleven test subjects. The results of the test areshown in FIG. 7. The sample diapers according to this example defined aWet Skin Temperature/Dry Skin Temperature ratio of 0.970.

Comparative Example 6

[0228] Samples of diapers having the same general construction as thediapers described in connection with Comparative Example 2 were made.The diapers were substantially the same as the Comparative Example 2diapers except the backsheet was replaced with a 1.0 mil thickpolyethylene film material having a water vapor transmission rate ofless than 100 grams per square meter per 24 hours. The diapers weresubjected to the Skin Temperature Test set forth above. The samples weretested on one of the forearms of each of eleven test subjects. Theresults of the test are shown in FIG. 7. The sample diapers according tothis example defined a Wet Skin Temperature/Dry Skin Temperature ratioof 1.014.

[0229] The test results from Example 15 as shown in FIG. 7 show thatdiapers made according to the present invention are capable ofmaintaining a more constant, reduced skin temperature when wet whencompared to conventional absorbent diapers and the test results fromComparative Example 6. It is hypothesized that the more constant,reduced skin temperature is achieved by reducing the occlusion of theskin by increasing the breathability of the diaper when wet. Moreover,as shown in FIG. 7, diapers made according to the present invention arecapable of maintaining a skin temperature when wet which issubstantially the same as the wearer's' undiapered skin temperature.Such a maintained skin temperature can result in improved comfort to thewearer.

[0230] Having thus described the invention in rather full detail, itwill be readily apparent to a person of ordinary skill that variouschanges and modifications can be made without departing from the spiritof the invention. All of such changes and modifications are contemplatedas being within the scope of the present invention as defined by thesubjoined claims.

We claim:
 1. A disposable absorbent article comprising an absorbent, afront waist section, a rear waist section and an intermediate sectionwhich interconnects said front and rear waist sections wherein saidabsorbent article defines a Wet Air Exchange Rate of at least about 190cubic centimeters per minute calculated according to a Tracer Gas Testset forth herein.
 2. The absorbent article of claim 1 wherein said WetAir Exchange Rate of said absorbent article is at least about 200 cubiccentimeters per minute calculated according to said Tracer Gas Test. 3.The absorbent article of claim 1 wherein said Wet Air Exchange Rate ofsaid absorbent article is at least about 225 cubic centimeters perminute calculated according to said Tracer Gas Test.
 4. The absorbentarticle of claim 1 wherein said Wet Air Exchange Rate of said absorbentarticle is at least about 250 cubic centimeters per minute calculatedaccording to said Tracer Gas Test.
 5. The absorbent article of claim 1wherein said absorbent article defines a Dry Air Exchange Rate of atleast about 525 cubic centimeters per minute calculated according tosaid Tracer Gas Test.
 6. The absorbent article of claim 2 wherein saidabsorbent article defines a Dry Air Exchange Rate of at least about 575cubic centimeters per minute calculated according to said Tracer GasTest.
 7. The absorbent article of claim 1 wherein said absorbent articledefines a Skin Hydration Value of less than about 18 grams per squaremeter per hour calculated according to a Skin Hydration Test set forthherein.
 8. The absorbent article of claim 1 wherein said absorbentarticle defines a Skin Hydration Value of less than about 15 grams persquare meter per hour calculated according to a Skin Hydration Test setforth herein.
 9. The absorbent article of claim 1 wherein said absorbentarticle defines a Skin Hydration Value of less than about 12 grams persquare meter per hour calculated according to a Skin Hydration Test setforth herein.
 10. A disposable absorbent article comprising anabsorbent, a front waist section, a rear waist section and anintermediate section which interconnects said front and rear waistsections wherein said absorbent article defines a Dry Air Exchange Rateof at least about 525 cubic centimeters per minute and a Wet AirExchange Rate/Dry Air Exchange Rate ratio of at least about 0.20calculated according to a Tracer Gas Test set forth herein.
 11. Theabsorbent article of claim 10 wherein said absorbent article defines aWet Air Exchange Rate of at least about 190 cubic centimeters per minutecalculated according to said Tracer Gas Test.
 12. The absorbent articleof claim 10 wherein said absorbent article defines a Wet Air ExchangeRate of at least about 225 cubic centimeters per minute calculatedaccording to said Tracer Gas Test.
 13. The absorbent article of claim 10wherein said Dry Air Exchange Rate of said absorbent article is at leastabout 575 cubic centimeters per minute calculated according to saidTracer Gas Test.
 14. The absorbent article of claim 10 wherein said DryAir Exchange Rate of said absorbent article is at least about 625 cubiccentimeters per minute calculated according to said Tracer Gas Test. 15.The absorbent article of claim 10 wherein said Wet Air Exchange Rate/DryAir Exchange Rate ratio of said absorbent article is at least about 0.23calculated according to said Tracer Gas Test.
 16. The absorbent articleof claim 10 wherein said Dry Air Exchange Rate of said absorbent articleis at least about 625 cubic centimeters per minute and said Wet AirExchange Rate/Dry Air Exchange Rate ratio of said absorbent article isat least about 0.23 calculated according to said Tracer Gas Test. 17.The absorbent article of claim 10 wherein said absorbent article definesa Skin Hydration Value of less than about 18 grams per square meter perhour calculated according to a Skin Hydration Test as set forth herein.18. The absorbent article of claim 10 wherein said absorbent articledefines a Skin Hydration Value of less than about 15 grams per squaremeter per hour calculated according to a Skin Hydration Test as setforth herein.
 19. The absorbent article of claim 16 wherein saidabsorbent article defines a Skin Hydration Value of less than about 15grams per square meter per hour calculated according to a Skin HydrationTest as set forth herein.
 20. A disposable absorbent article whichcomprises: a) a vapor permeable backsheet which defines a Water VaporTransmission Rate of at least about 1000 grams per square meter per 24hours calculated according to a Water Vapor Transmission Test as setforth herein; b) a liquid permeable topsheet which is positioned infacing relation with said backsheet; and c) an absorbent body locatedbetween said backsheet and said topsheet wherein said absorbent articledefines a Wet Air Exchange Rate of at least about 190 cubic centimetersper minute calculated according to a Tracer Gas Test as set forthherein.
 21. The absorbent article of claim 20 wherein said vaporpermeable backsheet is substantially liquid impermeable.
 22. Theabsorbent article of claim 20 wherein said vapor permeable backsheet isconstructed to provide a Hydrohead Value of at least about 60centimeters calculated according to a Hydrostatic Pressure Test as setforth herein.
 23. The absorbent article of claim 20 wherein said vaporpermeable backsheet is constructed to provide a Hydrohead Value of atleast about 80 centimeters calculated according to a HydrostaticPressure Test as set forth herein.
 24. The absorbent article of claim 20wherein said Water Vapor Transmission Rate of said vapor permeablebacksheet is at least about 1500 grams per square meter per 24 hourscalculated according to said Water Vapor Transmission Test.
 25. Theabsorbent article of claim 20 wherein said Wet Air Exchange Rate of saidabsorbent article is at least about 225 cubic centimeters per minutecalculated according to said Tracer Gas Test.
 26. The absorbent articleof claim 20 wherein said Wet Air Exchange Rate of said absorbent articleis at least about 250 cubic centimeters per minute calculated accordingto said Tracer Gas Test.
 27. The absorbent article of claim 20 whereinsaid absorbent article defines a Dry Air Exchange Rate of at least about525 cubic centimeters per minute calculated according to said Tracer GasTest.
 28. The absorbent article of claim 20 wherein said absorbentarticle defines a Skin Hydration Value of less than about 18 grams persquare meter per hour calculated according to a Skin Hydration Test asset forth herein.
 29. The absorbent article of claim 20 wherein saidabsorbent article defines a Skin Hydration Value of less than about 15grams per square meter per hour calculated according to a Skin HydrationTest as set forth herein.
 30. The absorbent article of claim 20 whereinsaid absorbent article defines a Skin Hydration Value of less than about12 grams per square meter per hour calculated according to a SkinHydration Test as set forth herein.
 31. The absorbent article of claim20 wherein said absorbent article defines a Wet Air Exchange Rate/DryAir Exchange Rate ratio of at least about 0.20 calculated according tosaid Tracer Gas Test.
 32. A disposable absorbent article comprising anabsorbent, a front waist section, a rear waist section and anintermediate section which interconnects said front and rear waistsections wherein said absorbent article defines a Skin Hydration Valueof less than about 18 grams per square meter per hour calculatedaccording to a Skin Hydration Test set forth herein.
 33. The absorbentarticle of claim 32 wherein said Skin Hydration Value of said absorbentarticle is less than about 15 grams per square meter per hour calculatedaccording to said Skin Hydration Test.
 34. The absorbent article ofclaim 32 wherein said Skin Hydration Value of said absorbent article isless than about 12 grams per square meter per hour calculated accordingto said Skin Hydration Test.
 35. The absorbent article of claim 32wherein said Skin Hydration Value of said absorbent article is less thanabout 10 grams per square meter per hour calculated according to saidSkin Hydration Test.
 36. The absorbent article of claim 32 wherein saidabsorbent article defines a Dry Air Exchange Rate of at least about 525cubic centimeters per minute and a Wet Air Exchange Rate of at leastabout 190 cubic centimeters per minute calculated according to a TracerGas Test as set forth herein.
 37. A disposable absorbent articlecomprising an absorbent, a front waist section, a rear waist section andan intermediate section which interconnects said front and rear waistsections wherein said absorbent article defines a Wet Air ExchangeRate/Dry Air Exchange Rate ratio of at least about 0.50 calculatedaccording to a Tracer Gas Test set forth herein.
 38. The absorbentarticle of claim 37 wherein said Wet Air Exchange Rate/Dry Air ExchangeRate ratio is at least about 0.70 calculated according to said TracerGas Test.
 39. The absorbent article of claim 37 wherein said Wet AirExchange Rate/Dry Air Exchange Rate ratio is at least about 0.80calculated according to said Tracer Gas Test.
 40. The absorbent articleof claim 37 wherein said Wet Air Exchange Rate/Dry Air Exchange Rateratio is at least about 0.90 calculated according to said Tracer GasTest.
 41. The absorbent article of claim 37 wherein said Wet AirExchange Rate/Dry Air Exchange Rate ratio is at least about 1.00calculated according to said Tracer Gas Test.
 42. The absorbent articleof claim 37 wherein said absorbent article defines a Wet Air ExchangeRate of at least about 190 cubic centimeters per minute calculatedaccording to said Tracer Gas Test.
 43. The absorbent article of claim 37wherein said absorbent article defines a Wet Air Exchange Rate of atleast about 200 cubic centimeters per minute calculated according tosaid Tracer Gas Test.
 44. The absorbent article of claim 37 wherein saidabsorbent article defines a Wet Air Exchange Rate of at least about 225cubic centimeters per minute calculated according to said Tracer GasTest.
 45. The absorbent article of claim 37 wherein said absorbentarticle defines a Dry Air Exchange Rate of at least about 200 cubiccentimeters per minute calculated according to said Tracer Gas Test. 46.The absorbent article of claim 39 wherein said absorbent article definesa Dry Air Exchange Rate of at least about 200 cubic centimeters perminute calculated according to said Tracer Gas Test.
 47. The absorbentarticle of claim 37 wherein said absorbent article defines a SkinHydration Value of less than about 18 grams per square meter per hourcalculated according to a Skin Hydration Test set forth herein.
 48. Theabsorbent article of claim 37 wherein said absorbent article defines aSkin Hydration Value of less than about 15 grams per square meter perhour calculated according to a Skin Hydration Test set forth herein. 49.The absorbent article of claim 37 wherein said absorbent article definesa Skin Hydration Value of less than about 12 grams per square meter perhour calculated according to a Skin Hydration Test set forth herein. 50.The absorbent article of claim 37 wherein said absorbent article definesa Skin Hydration Value of less than about 10 grams per square meter perhour calculated according to a Skin Hydration Test set forth herein. 51.The absorbent article of claim 37 wherein said article comprises: a) avapor permeable backsheet which defines a Water Vapor Transmission Rateof at least about 1000 grams per square meter per 24 hours calculatedaccording to a Water Vapor Transmission Test as set forth herein; b) aliquid permeable topsheet which is positioned in facing relation withsaid backsheet; and c) an absorbent body located between said backsheetand said topsheet.
 52. The absorbent article of claim 51 wherein saidWater Vapor Transmission Rate of said vapor permeable backsheet is atleast about 1500 grams per square meter per 24 hours calculatedaccording to said Water Vapor Transmission Test.
 53. The absorbentarticle of claim 51 and further comprising a ventilation layer locatedbetween said backsheet and said absorbent body.
 54. The absorbentarticle of claim 53 wherein said ventilation layer comprises ahydrophobic, nonwoven material having a thickness of at least about 0.10centimeters and a basis weight of from about 20 to about 120 grams persquare meter.
 55. The absorbent article of claim 53 and furthercomprising a surge management layer which is located between saidtopsheet and said absorbent wherein said surge management layercomprises a nonwoven material having a basis weight of from about 30 toabout 120 grams per square meter.
 56. A disposable absorbent articlewhich comprises: a) a vapor permeable backsheet which defines a WaterVapor Transmission Rate of at least about 1000 grams per square meterper 24 hours calculated according to a Water Vapor Transmission Test asset forth herein; b) a liquid permeable topsheet which is positioned infacing relation with said backsheet; and c) an absorbent body locatedbetween said backsheet and said topsheet wherein said absorbent articledefines a Wet Air Exchange Rate/Dry Air Exchange Rate ratio of at leastabout 1.00 calculated according to a Tracer Gas Test set forth herein.57. The absorbent article of claim 56 wherein said Wet Air ExchangeRate/Dry Air Exchange Rate ratio is at least about 1.05 calculatedaccording to said Tracer Gas Test.
 58. The absorbent article of claim 56wherein said Wet Air Exchange Rate/Dry Air Exchange Rate ratio is atleast about 1.10 calculated according to said Tracer Gas Test.
 59. Theabsorbent article of claim 56 wherein said absorbent article defines aDry Air Exchange Rate of at least about 200 cubic centimeters per minutecalculated according to said Tracer Gas Test.
 60. The absorbent articleof claim 56 wherein said absorbent article defines a Dry Air ExchangeRate of at least about 225 cubic centimeters per minute calculatedaccording to said Tracer Gas Test.
 61. The absorbent article of claim 56wherein said absorbent article defines a Dry Air Exchange Rate of atleast about 250 cubic centimeters per minute calculated according tosaid Tracer Gas Test.
 62. The absorbent article of claim 56 wherein saidabsorbent article defines a Skin Hydration Value of less than about 18grams per square meter per hour calculated according to a Skin HydrationTest set forth herein.
 63. The absorbent article of claim 56 whereinsaid absorbent article defines a Skin Hydration Value of less than about15 grams per square meter per hour calculated according to a SkinHydration Test set forth herein.
 64. The absorbent article of claim 56wherein said absorbent article defines a Skin Hydration Value of lessthan about 12 grams per square meter per hour calculated according to aSkin Hydration Test set forth herein.
 65. The absorbent article of claim56 wherein said Water Vapor Transmission Rate of said vapor permeablebacksheet is at least about 1500 grams per square meter per 24 hourscalculated according to said Water Vapor Transmission Test.
 66. Adisposable absorbent article which defines a front waist section, a rearwaist section, and an intermediate section which interconnects saidfront and rear waist sections, said absorbent article comprising: a) avapor permeable backsheet which defines a Water Vapor Transmission Rateof at least about 1000 grams per square meter per 24 hours calculatedaccording to a Water Vapor Transmission Test as set forth herein; b) aliquid permeable topsheet which is positioned in facing relation withsaid backsheet; and c) an absorbent body located between said backsheetand said topsheet, wherein at least a portion of said absorbent bodycontracts in at least one of a machine direction and a cross machinedirection at least about 5 percent when subjected to at least one ofmoisture vapor and moisture.
 67. The absorbent article of claim 66wherein said absorbent body includes a plurality of segments and saidcontraction of said absorbent body provides zones of high airpermeability between said segments.
 68. The absorbent article of claim67 wherein said segments are spaced apart in a longitudinal directionalong said absorbent article.
 69. The absorbent article of claim 67wherein said zones of high air permeability define a total surface areaof at least about 10 percent of a total surface area of said absorbentbody.
 70. The absorbent article of claim 67 wherein said zones of highair permeability are located in said intermediate section and said frontwaist section of said absorbent article and not in said back waistsection.
 71. The absorbent article of claim 66 wherein said portion ofsaid absorbent body contracts in at least one of said machine directionand said cross machine direction at least about 10 percent.
 72. Theabsorbent article of claim 66 wherein said absorbent body includeselastomeric fibers.
 73. The absorbent article of claim 66 wherein saidabsorbent article defines Wet Air Exchange/Dry Air Exchange ratio of atleast about 0.50 calculated according to a Tracer Gas Test set forthherein.
 74. The absorbent article of claim 66 wherein said absorbentarticle defines Wet Air Exchange/Dry Air Exchange ratio of at leastabout 0.70 calculated according to a Tracer Gas Test set forth herein.75. The absorbent article of claim 66 wherein said absorbent articledefines a Skin Hydration Value of less than about 18 grams per squaremeter per hour calculated according to a Skin Hydration Test set forthherein.
 76. The absorbent article of claim 66 wherein said absorbentarticle defines a Skin Hydration Value of less than about 15 grams persquare meter per hour calculated according to a Skin Hydration Test setforth herein.
 77. The absorbent article of claim 66 wherein said WaterVapor Transmission Rate of said vapor permeable backsheet is at leastabout 150.0 grams per square meter per 24 hours calculated according tosaid Water Vapor Transmission Test.
 78. The absorbent article of claim66 and further comprising a ventilation layer located between saidbacksheet and said absorbent body.
 79. The absorbent article of claim 78wherein said ventilation layer comprises a hydrophobic, nonwovenmaterial having a thickness of at least about 0.10 centimeters and abasis weight of from about 20 to about 120 grams per square meter. 80.The absorbent article of claim 78 and further comprising a surgemanagement layer which is located between said topsheet and saidabsorbent wherein said surge management layer comprises a nonwovenmaterial having a basis weight of from about 30 to about 120 grams persquare meter.